The People's Liberation Army (PLA) soldiers, numbering about 20, were among those who were out in force to remove bricks and other objects strewn on several main roads near different universities in Hong Kong, Efe news reported.
Traffic resumed as a result of their actions but tension still hovered in the air as the protest movement entered its 24th consecutive week.
It was the first time the Chinese soldiers appeared in public in Hong Kong to carry out an operation since the anti-government protest movement erupted in June. They made their appearance near Baptist University in Kowloon Tong Saturday afternoon without warning, and reportedly claimed that they made the move on their own volition.
Any move made by Chinese troops in the semiautonomous territory, which is run under a so-called "one country, two systems" principle, is a touchy matter.
Since the beginning of the protests, there have been speculations from time to time that Beijing might send in troops to Hong Kong to crack down on the movement, which was triggered by a now-withdrawn bill on extradition from Hong Kong to mainland China.
According to Hong Kong's mini constitution, the PLA troops can be called out to help with disaster relief or maintaining public order if requested by the Hong Kong government.
In the morning, Tolo Highway, an all-important road near the Chinese University of Hong Kong in the New Territories, was cleared of debris and reopened four days after students blocked it with a variety of objects to bring traffic to a halt.
Nonetheless, the Cross-Harbour Tunnel, a key artery connecting Kowloon and Hong Kong Island, remained blocked by barricades erected by students from the nearby Polytechnic University.
In the upper middle class area of Pok Fu Lam near the University of Hong Kong (HKU), hundreds of bricks which were laid out on a main road as triathlons - a striking spectacle that was also seen in the core financial district of Central over the past few days - were cleared by a group of local residents who were angry with the students' actions.
"You are trash! Do you know you are very selfish by blocking the road?" a disgruntled man shouted at a group of young people as he removed a brick from the road. Others chanted slogans such as "support Hong Kong police". Over the past five months, the police have arrested more than 3,000 people in protests, many of them young protesters.
Among the crowd watching cleaners remove the bricks was a HKU teacher who did not want to be identified.
He told Efe: "I think one can be more rational. I understand the students feel they need to up the ante because the government has not responded to any of their demands and not a single government official has stepped down. But I tell them there can be better ways to express themselves than block the roads."
Tension returned in early evening when police vehicles arrived, leading to a standoff with black-clad students who took refuge on a footbridge on the campus.
The clearance operations came after the heads of nine public universities released a statement Friday that said university campuses had been caught up in political struggle and called for the government to take the lead to restore public order and stability.
Over the past few days, main arteries near four universities across Hong Kong were blocked by makeshift barricades put up by university students, partly because of the general strike that began on Monday, and partly because students wanted to keep police at bay after the latter stormed into their campuses and fired teargas.
Hong Kong's anti-government protesters initiated the general strike after a 22-year-old university student died from brain injuries on November 8 following his fall from a carpark under unclear circumstances during a protest.
The strike got off to a violent start Monday morning when a young protester trying to block a busy road was shot in the chest by police.
The next few days were marred by fierce protests involving everything from students to bankers, as well as a spate of violent incidents.
A man was set on fire after he allegedly attempted to attack protesters with a knife.
A 70-year-old man died hours after being hit in the head by a brick during a scuffle with anti-government protesters, sparking harsh criticism from Hong Kong and Chinese officials.
A 15-year-old orphan was also allegedly shot in the eye and seriously injured by police projectile.
( With inputs from IANS )