SHANGHAI (AFP) - A coastal Chinese city was under lockdown on Wednesday after reports of a violent protest involving thousands of people over slow relief work following a typhoon, residents and state media said.

Residents of Yuyao were demonstrating against what they called a delayed response to Typhoon Fitow, including cleaning up flooding and restoring power, the Global Times newspaper said.

The typhoon, which made landfall on October 7, killed at least 10 people, state media has previously reported.

Yuyao, in the eastern province of Zhejiang north of Ningbo city, was hit by flooding from the typhoon with some water still remaining in older neighbourhoods, residents said.

Protests appeared to have ebbed on Wednesday in the face of a strong police presence, they added.

"There are lots of riot police in front of the city government building now, due to the petition yesterday," a resident said.

Residents were quoted by the Global Times as saying authorities detained "several" people on Tuesday for throwing rocks at police and overturning government vehicles.

Photos circulating on microblogs, reportedly from the scene on Tuesday, showed massed civilians destroying vehicles and lines of police with riot shields and helmets.

Police and the local government could not be reached for comment on Wednesday.

An editorial published in a government-run local newspaper Wednesday urged residents to be calm.

"It is understandable that those who suffered losses have complaints...

However, reasonable demands must be raised through normal channels," the Yuyao Daily said.

"Impulsive or aggressive behaviour is not the way for expressing demands, let alone solving problems," said the editorial, which the Yuyao government posted on its official microblog.