Taxi drivers smashed car windows and police vehicles as they went on a rampage through Chongqing yesterday, the Xinhua News Agency reported.

Thousands of drivers in the city were protesting over increased operating costs, shortages of natural gas and high traffic fines, it said.

They are also unhappy about the government's lack of effort to stop unlicensed taxis operating in the city, Xinhua claimed.

Some angry drivers smashed the windows of other taxis that tried to cross picket lines, and even pulled drivers out of those vehicles, it said.

At least 20 vehicles, including three police cars, were damaged, the report said.

More than 100 people, mostly taxi drivers, gathered on a street in the city's Jiangbei district at about 11:30 am, Xinhua reported.

"All drivers agreed to stop work, so we damaged the cabs of those who didn't keep their word," one protestor, who refused to give his name, told Xinhua.

Zhang Yujun, vice-director of the municipal transport administration said some drivers wanted to work but were unable to do so because of the protest.

"A lot of taxi drivers didn't want to join the strike, but they were worried their cars would be damaged if they didn't," a driver named Huang was quoted as saying.

The absence of taxis left thousands of commuters in the city stranded, the report said.

The Chongqing transport administration held an emergency meeting after the protest began and asked the taxi drivers to return to work.

Zhou Bo, vice-publicity director of the CPC Chongqing municipal committee said Party officials and the government held several meetings yesterday afternoon and issued a series of measures to get the taxi drivers back to work, the report said without giving any details.

Zhou said police should keep traffic flowing and should penalize unlicensed cab drivers.

He promised an investigation will be held into the price of natural gas.

About 800 drivers returned to work at about 2 pm yesterday.

Chongqing has 16,000 licensed cabs, Xinhua said, with about 9,000 of them operating in the city's urban areas.