The liaison office said on Saturday about 600 volunteers participated in the eight-hour effort. Of that total, more than 400 were PLA soldiers, according to TVB. The aim was to clear the trail ahead of a 100km race to be held on it.

PLA Hong Kong garrison deputy commander Tian Yongjiang also joined the effort, and was pictured giving commands in his uniform bearing a PLA badge.

However, the Agriculture, Fisheries and Conservation Department announced the trail had been cleared and reopened on Friday.

It was the first time troops were seen taking part in post-typhoon clean-up work in Hong Kong.

Monster storm Mangkhut battered the city on September 16, with the highest typhoon signal, No 10, issued for 10 hours. Public transport, services and businesses were paralysed for about two days.

Speaking after a Commercial Radio programme on Sunday, Cheung said Hongkongers should not “read too much into” what the PLA did, as it was “intended for Hong Kong’s good”.

The city’s No 2 official said the soldiers were only taking part in a voluntary community service organised by Beijing’s liaison office and a group of local Chinese businesses.

“The [Hong Kong] government did not interfere with their activity. We did not play any role,” Cheung added. “Our police, disciplined services, and our colleagues also took part in voluntary services. These things happen, so do not read too much into this. The government did not ask the PLA for help.”

The PLA garrison maintains a low profile, with soldiers confined to the 23 barracks in Hong Kong.

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Open days are held at military sites each year to mark the handover in 1997, giving the public a brief look at the armed forces.

Under the Garrison Law, the PLA must not interfere in local affairs, but troops can be called out to help with disaster relief if requested by the Hong Kong government. The central government would have to approve the request and the troops would have to return to barracks immediately upon completion of the tasks.

Retired journalist Forever Sze Wing-yuen ran into two teams of 30 soldiers on Saturday afternoon at Pak Tam Au, Sai Kung. Sze said they wore uniforms but he was not sure if they had PLA badges. Photos uploaded to the liaison office showed soldiers wearing PLA badges.

“They were carrying saws and shovels, and seemed to be resting after clearing branches of uprooted trees,” Sze said.

“They were very quiet and looked calmly cautious, not even talking to each other, but I noticed they were sitting side by side in teams.

“I have never seen a PLA solder outside barracks, not to mention in a PLA uniform.”

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The 100km hiking trail crosses much of the New Territories, from Sai Kung to Tuen Mun.

Yang Yirui, the foreign ministry’s deputy commissioner in Hong Kong, said to the TV station: “We live and work in Hong Kong. We are all Chinese. Therefore we always see Hong Kong as our home.”

Military expert Leung Kwok-leung said it was “legally sound” for the garrison in Hong Kong to volunteer in the public interest but the liaison office and government could have done better in telling the public.

“What the Hong Kong garrison soldiers did was different from the disaster relief tasks carried out by their peers in Macau upon the government’s request,” Leung said.

“It has been quite a while since Mangkhut left and it was not the first time the Hong Kong garrison soldiers took part in public-interest activities, such as blood donation.”

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Whether there were communications between the government and garrison regarding the plan was unclear. But Leung said: “They should have communicated if they were detail-minded and sufficiently careful about the political sensitivity. And they could have informed the public in advance.”

As of August, soldiers in Hong Kong had taken part in annual tree-planting activities 18 times and donated blood 20 times, according to Xinhua.

A government spokesman said the liaison office’s volunteer team coordinated the clean-up rather than it being a request for help. There was no response on whether the government and liaison office communicated ahead of the work or if the arrangement breached the Garrison Law.

Additional reporting by Tony Cheung