The New Delhi-based Committee for the Release of Political Prisoners (CRPP) has launched a national campaign to lobby the Indian government to recognise thousands of political prisoners as a separate category of detainees. The CRPP, which alleges detainees are routinely tortured, estimates that India has more than 10,000 political prisoners and the number is rising as state governments act increasingly to crush dissent.

Although law and order is vested with individual states in India, CRPP activists say reform at the central or federal level - including giving those held for their political views legal status - is crucial to protect them from abuse.

India ratified the International Covenant on Civil and Political Rights in 1979. But CRPP campaigners claim that dissidents lack protection as Indian legislation has not been adapted to recognise political prisoners.

CRPP vice-president Syed Abdul Rahman Geelani said: 'As a political prisoner you are almost always mistreated. It's a rare occasion when you are treated well. These are not isolated incidents. It's a well thought out strategy. It's systematically being done. The system evolves at state level but if the centre [New Delhi] wanted to help, they could do something.'

The CRPP has held awareness-raising programmes to educate people about political prisoners and allegations of abuse. It has lobbied lawmakers and plans to push state governments to allow access to detainees. The aim is to document the number of such prisoners and the condition they are in.

It was open criticism of the Chhattisgarh state government that led to Sen's detention, his supporters say.

Two years ago, the paediatrician visited Maoist ideologue Narayan Sanyal, who is in prison in Raipur facing a murder charge. Helping Maoist organisations, considered by New Delhi to be terrorist groups, is deemed illegal. Armed Maoist guerillas are fighting insurgencies in large swathes of India, including Chhattisgarh.

Sen first came to prominence for his work in the health sector, helping hundreds of people in Chhattisgarh's impoverished tribal communities. He and his wife, Ilina Sen, formed an NGO called Rupantar in 1995 to provide low-cost medicine to tribal residents and to train people in around 20 villages to be health workers.

Sen became a human rights campaigner in 2000. As vice president of the New Delhi-based People's Union for Civil Liberties (PUCL), he condemned the Salwa Judum - a militia funded by the Chhattisgarh state and Indian governments. Human rights workers have accused both the Maoists and the Salwa Judum of widespread abuses, including rape, torture and murder.

Campaigners, including Sen, allege the Chhattisgarh government supports Salwa Judum's activities with New Delhi's backing.

The state government confirms it funds and organises Salwa Judum and New Delhi admits giving some counter-insurgency funding. But both deny the militia has been responsible for human rights abuses.

As PUCL vice-president and as a doctor, Sen often visited detainees including Sanyal, to monitor their treatment and push for improvements in prison conditions, his family says. The state government alleges Sen used the visits to carry messages from Sanyal to other Maoist leaders.

Sitting in their home with their daughters Pranhita and Aparajita in Raipur, Professor Sen said: 'Dr Sen's trial is a political trial ... The forces that are trying to crucify Binayak Sen go beyond the evidence and the witnesses.

'He was critical of the Salwa Judum and the lack of health care at a very basic level, so he was a dangerous person because he asked the wrong questions. At the most you could say he was foolish. Why did he meet Sanyal? But he believed [that] in a democratic country, he could visit anyone in prison. He stood up for his convictions. ... That was the extent of his crime,' said Professor Sen, who teaches at the Mahatma Gandhi International Hindi University in Maharashtra state.

More than 2,000km away in the village of Dewar, Indian Kashmir, Shaheena Akhtar Untoo did not think it strange when her husband, human rights worker Mohammed Ahsan Untoo, went to New Delhi in February 2005. He was there, she said, to lodge some complaints with the National Human Rights Commission. As the days passed, she waited in vain for her husband to return.

On February 9, 2005, officers from the counterterrorism unit of the Delhi police picked up Untoo, who used to be a militant with the Pakistan-based Hizb-ul-Mujahideen, which fought against New Delhi's control of Indian Kashmir, before he became a human rights activist. The insurgency in Indian Kashmir, which began in 1989 when armed militias began resisting New Delhi's rule of the disputed region, has killed more than 60,000 people.

His detention that day was not recorded in police records, his lawyer said. For four days, Untoo was officially 'off-radar' and held in custody in a Delhi police station where, he alleged, he was sexually assaulted. When he appeared before a magistrate in the capital, he was charged under two sections of the Official Secrets Act. The police claim he was carrying classified information, including a map of army units deployed in Indian Kashmir and 70,000 rupees (HK$12,750) alleged to have been given to him by an agent from Pakistani intelligence via its embassy.

Untoo denies the charges. His defence counsel claimed Untoo was framed and that he was tortured and made to sign a blank statement. His trial began last year at the Sessions Court in New Delhi and is due to last another two years. Denied bail because of the gravity of his alleged crimes, he faces up to 14 years in jail if convicted.

Ms Untoo, a mother of four, said: 'We would never have thought that in three years we would still be waiting. I live in hope that tomorrow or the next day he will come. The older children understand, the younger ones don't. My youngest son asks me, 'Where is my dad?'. I have to tell him, 'He will come tomorrow or the next day'.'

After giving up militancy in 1992, Untoo campaigned for the rights of the families of men and boys who had disappeared since the insurgency erupted in the region and highlighted custodial deaths in the state.

He staged protests in Indian Kashmir to highlight human rights abuses until his arrest in 2005, criticising army personnel, police officers and politicians. His refusal to be silenced led to his detention, he said.

'I'm here because of my human rights work, because I'm a Kashmiri. Because I was doing human rights work, because I was doing that I was arrested.

'They forced me to drink alcohol to try to break me. Then they sodomised me. To live as a human being is difficult here. [The] inhuman and barbaric acts against our religion, Islam, drinking alcohol, they made me do,' he said at the chief judicial magistrate's court in Srinagar, where he is standing trial.

He was accused of rioting, wrongful restraint, minor injury and endangering the life or the personal safety of others after he took part in a public protest in Srinagar in 2004. He denies the charges.

Untoo filed a petition at New Delhi's Chief Metropolitan Magistrate's Court in March 2005 alleging he had been sexually assaulted in custody. Judges ruled the petition would be heard as part of his Delhi trial proceedings.

Police deny the allegations. Alok Kumar, Delhi police special cell spokesman, said: 'These are allegations which criminals and terrorists use to get bail from the courts. The allegations are baseless.'

A similar curt response came from the Chhattisgarh government over Sen's fate. Sanjay Pillai, a secretary at the state's home department, said: 'We can't give you any details on the trial in the court, because the matter is sub judice.'

Kamal Mitra Chenoy, a professor of comparative and Indian politics at New Delhi's Jawaharlal Nehru University, said New Delhi could use article 257 of the constitution to order state governments to act in a certain way if it believed their behaviour was 'prejudicial to the federal government's actions'.

But he said New Delhi had never used that power to force states to toe the line in human rights cases. He said the Indian government had 'never treated human rights as a serious problem. Just like the mentality of the United States changed considerably after 9/11, the mentality of the Indian state changed after 1990, when the insurgency broke out in Kashmir. It's part of the 'national security syndrome', which has become stronger in India with the terrorism and militancy'.

India's home ministry has refused to comment on CRPP's demand that the federal authorities should do more to ensure states safeguard the rights of political prisoners and that New Delhi officially recognise such prisoners. Ministry spokesman Onkar Kadia refused to comment on either Sen's or Untoo's cases, saying the matters were sub judice.

Professor Sen is highly critical of the intolerance of dissent in the world's largest democracy.

'The state is trying to suppress dissent but I don't think it will work,' she said. 'There is a paranoia ...[but] the 'fear factor' won't work. We have to break that.'