Han Fengqun, 56, was found at 2pm in a shipping container 50 metres from the centre of the blast area, according to state broadcaster CCTV.

He was found by troops trained in chemical defence and warfare under a pile of shipping containers that had been buckled by the force of the blasts on Wednesday night.

They had been searching through the containers by torchlight before they found him, the report said.

He was still conscious and able to say a few words before he was taken to a military hospital.

China News Service reported he was in critical condition and suffering from severe dehydration and respiratory failure. Doctors earlier said he had suffered burns to his throat and lungs, plus several fractures to his body.

Han comes from Henan  province and had been running a grocery business in the city’s port for two years.

State television said he had spoken to his family by phone on Wednesday night before the blasts and then went missing.

The chemical defence force of the Beijing garrison started their search at noon after receiving a report that another resident, an employee working for a logistics company at the port, was still missing.

A team of 70 chemical warfare troops searched the area looking for survivors, Xinhua said.

He suffered burns to his face and eyes as well as fractured ribs, state media reported.

Meanwhile, as new explosions rocked the site on Saturday, some residents were told to stay indoors or voluntarily left temporary shelters due to changes in the wind direction, amid lingering concerns about a chemical contamination in the industrial zone.

Despite rumours and news reports that an evacuation had been enacted for a radius of up to 3 kilometres, a government official in Tianjin denied that this was the case. 

Seven or eight fresh blasts caused new fires to break out at the facility in the port city, the state news agency Xinhua reported. It did not give details about the scale of the latest explosions.

As the list of casualties count continued to grow, the Pope offered prayers in Rome for the victims and their families.

"Those who have lost their lives as well as all those touched by this catastrophe are in my prayers," Pope Francis said during angelus prayers at St  Peter's in Rome during the Catholic Feast of the Assumption, which marks Christ's mother Mary's ascent to heaven.

Starting from 11am, police and volunteers with loudspeakers were telling Tianjin residents to start evacuating the danger zone, The Beijing News reported on its news website.

However, some residents had reportedly returned later in the day after the wind direction changed again.

Police blocked Donghai Road, the main road leading to the blast zone. At the same, teams in vehicles were seen clearing paths for rescue efforts.

Thirteen firefighters and an unknown number of port workers were still missing, Xinhua reported.

One firefighter was rescued from the ruins of the warehouse early Friday morning.

The disaster started when two explosions with a combined force of 24 tonnes of TNT ripped through the industrial Binhai New Area, burning everything in its path and damaging infrastructure up to 1 kilometre away, including surround apartment blocks.

At least 721 people were injured when explosions and a fireball hit the warehouse late Wednesday. Twenty-five were critically wounded and another 33 were in a serious condition, Xinhua said.

More than 1,000 rescuers were proceeding slowly in uncertain conditions where unidentified hazardous substances triggered the explosion, authorities said.

Armed police were carrying out the evacuation after highly poisonous sodium cyanide was found at the site, The Beijing News said, as the blaze intensified  dramatically, with several blasts reportedly heard.

“Out of consideration for toxic substances spreading, the masses nearby  have been asked to evacuate,” Xinhua said.

Officials said earlier that specialists from sodium cyanide producers were being sent in to the hazardous goods storage facility where giant explosions days earlier sent a huge fireball soaring into the sky and left a vast radius of destruction.

Authorities have struggled to control the resulting days-long blaze and  identify the substances present at the scene, sparking fears among locals.

Furious residents and victims’ relatives railed against officials outside a  news conference for keeping them in the dark as criticism over a lack of  transparency mounted. There were 21 firefighters among the dead, authorities said.

They were prevented from entering the briefing and could be heard shouting outside.

“Nobody has told us anything, we’re in the dark, there is no news at all,”  screamed one middle-aged woman, as she was dragged away by security personnel.

Officials said they were unable to identify precisely what chemicals were  at the site at the time.

At the news conference, Tianjin work safety official Gao Huaiyou listed a  host of possible substances, adding that recent large exports that passed through the site had included sodium bisulfide, magnesium, sodium, potassium  nitrate, ammonium nitrate, and sodium cyanide, among others.

“We believe there should still be a lot stored at the terminal areas,” he  said.

Personnel from sodium cyanide producers had been called in “because they are experts on the chemical’s nature and the ways to deal with it”, he added.

A sewage pipe where the chemical had reportedly been detected had been sealed off, he said.

More than 200 nuclear and biochemical experts from the Chinese military were deployed to Tianjin, which has a population of 15 million, on  Thursday.

Concerns about the chemical cocktail also raised questions over whether firefighters responding to an initial blaze at the warehouse could have contributed to the detonations by spraying water over substances that react explosively to it.

One senior official insisted firefighters had followed the proper  procedures, but noted that they were unaware of the precise chemicals present  when they arrived.

“It is not clear whether a chemical reaction occurred,” said Lei Jinde, the head of the firefighting department at Tianjin’s public security bureau.

“We knew there was calcium carbide, but we don’t know whether the calcium  carbide exploded and caught fire,” he said in an interview published by Xinhua. “It is not that the firefighters were fools ... No, it is not that.”

Lei said that the facility was listed as holding ammonium nitrate and  potassium nitrate, as well as calcium carbide.

State newspaper The People’s Daily said earlier that the facility’s construction “clearly  violated” safety rules. 

Under Chinese regulations, warehouses stocking dangerous materials must be at least one kilometre away from surrounding public buildings and  main roads, it said, but there were two residential compounds and several main  roads within that distance.

INFOGRAPHIC: The toxic cocktail in warehouse at centre of fatal explosions in Tianjin, China