The New Year's Eve crush that killed 36 people in Shanghai was a "bloody lesson" for the city, the mayor of China's commercial hub said Tuesday according to official media.

The comments by mayor Yang Xiong are an implicit acknowledgement that the events of December 31 should have been handled differently.

New Year revellers had flocked to the Bund, Shanghai's historic waterfront, but massive overcrowding caused people to be trampled, raising questions over why authorities failed to enforce better safety measures.

"Although the cause of the incident is still to be confirmed by investigation... we must learn from the bloody lesson, as well as deeply reflect on this matter," Yang told lawmakers, according to the official Xinhua news agency.

He did not say what agencies were carrying out what he described as a "joint investigation".

Yang also ordered an overhaul of emergency plans for handling large crowds, Xinhua said.

Some 25 of the 36 who died were female, and all but five of the total number were aged 25 or under, the Shanghai government has said.

They included one Malaysian woman and a woman from Taiwan, it said. The youngest victim was a 12-year-old boy and the oldest was 37.

The dead included students from three universities in Shanghai, according to Xinhua.

Relatives and friends of the victims visited the site on the Bund under the watchful eyes of government-assigned minders on Tuesday -- the seventh day after the incident which caused the deaths, a date with special meaning under traditional Chinese mourning customs.

"We went to the Bund in separate groups, and someone escorted us there and took us back afterwards," one said.

The sister of one victim has told AFP that her family will not hold a funeral until the government has explained how the accident could have happened.

Relatives said Tuesday that the government has yet to offer compensation packages to the families of the victims.

The accident, which has tarnished Shanghai's reputation as China's most international city, is the city's worst since a fire in a high-rise residential building killed 58 people in 2010.