Eyewitnesses described chaos at the scene as people struggled to move. Photo: BBC NEWS

Investigations are likely to examine whether there were enough police on duty to manage the huge crowds.

New Year's Day festivities in the city have been cancelled, Chinese media say.

'People screaming'

Mr Xi told Shanghai officials to provide an explanation for Wednesday's fatalities as soon as possible, state TV reported.

Local officials around China were also told to ensure no repeat of the Shanghai incident could occur elsewhere, Reuters said.

The crush began at about 23:35 local time (15:35 GMT) on Wednesday, Shanghai government officials and police said.

The incident centred on a stairway leading to a viewing platform near the waterfront, as people tried to get up and down the steps, state broadcaster CCTV said.

A local resident, identified as Sarah, told AFP news agency "people were screaming... and people [started] jumping off the staircase to get clear."

She added: "There was a quiet, and then people on the stairs fell in a wave."

Gaby Gabriel, an American photographer living in Shanghai, told the BBC: "It was a tremendous amount of people moving in all different directions.

"It seemed some people were trying to move away from the river and some people were trying to go towards the river and there was no order whatsoever, no guidance."

However, Shanghai police denied social media reports that a stampede was triggered by people stopping to pick up fake money thrown from the balcony of a nightclub.

In a statement, police said that video footage showed that the bills had been thrown after the crush took place.

A memorial has been set up on the Bund

Shanghai's city government said that the identification process for victims of the crush had begun.

A Taiwanese person was among the dead, and there were two Taiwanese and one Malaysian among the injured, it added.

Many of the dead are believed to be students, with 25 of them women, state media report.

Unexpected crowds?

Investigations are expected to examine how Shanghai police deployed officers to manage the new year crowds.

A traditional new year fireworks display on the Bund had already been cancelled due to official fears of overcrowding, the Shanghai Daily reports.

The BBC's John Sudworth in Shanghai says the investigation may focus on why so many people turned out despite the cancellation and whether there were enough police resources in place to look after them.

A police presence remained at the site on Thursday

Cai Lixin, a district police commander, said in quotes carried by Chinese media that there had been more people on the streets than during China's 1 October national day celebrations, but fewer police had been deployed.

"There were no formal events planned yesterday, so we did not arrange for as many police officers as last year's national day," he said.

However, despite the cancellation, state-run Xinhua news agency said there were "far more" people in the Bund area on Wednesday night than originally predicted, with a crowd size similar to the countdown in 2013.

According to the Shanghai Daily, close to 300,000 people turned up for New Year's Eve celebrations a year ago.

During a news conference on Thursday, Shanghai police said that about 500 additional officers had been mobilised following the crush.