A teacher, who was among the staff who organised the activity, told the that most of the victims were not badly hurt, though some injuries were deemed serious.

There were about 100 police and security guards at the stadium, but the teacher said they had not expected a huge crowd of outsiders to come.

Beckham, who is in China on a seven-day tour to promote the Chinese Super League, was forced to leave a few minutes later due to the chaos.

He said in a statement posted on the microblogging service Sina Weibo that he hoped the injured people recovered quickly.

"Anti-riot police were needed to fend off the overexcited fans," said Tony Ma, a young player who was on the pitch, waiting for some training tips from Beckham. "We were stunned by the female fans who came for the handsome face rather than the sport."

Jiang Ming, a university student, said: "The situation was desperate and the security personnel could have stopped the onrushing fans. I felt regretful because we missed the chance to stay longer with our idol."

The teacher said the university underestimated the enthusiasm for soccer.

The former England captain faces a tough task with local soccer still embroiled in controversy following a long line of graft scandals. Last week the national team suffered a humiliating 5-1 home defeat to Thailand in a friendly.

"When I first came on as ambassador of the Super League, I was well aware of what has happened in the past, and people question why I wanted to be involved in something that in the past had a bad name or corruption involved," Beckham told reporters in Shanghai.

"For me, the past is the past, this is the future."