Scuffles broke out at one ticket site as officials opened additional sales windows at the last minute, causing some fans to stampede ahead of others in a bid to buy some of the 250,000 tickets that went on sale in different parts of the host city.

"It was so unfair," said Ji Liqiang, who waited for 28 hours with Wang Zhenqiang, a fellow businessman from eastern Shandong province, for a chance to buy tickets to the diving competition.

"Those who came late but were able to push forward got the tickets," he said.

The two lost their place in line in the scramble and instead of tickets to the diving - where China is a gold-medal favourite - they ended up with tickets to the synchronised swimming.

"It was very dangerous. I was afraid," Wang said. "People got hurt around me. They fell and injured their knees and elbows. A barricade was bent out of shape by the crowd."

Several Hong Kong media workers complained about being pushed around by security officials.

Footage from Hong Kong Cable TV showed a policeman putting his arm around the neck of a Hong Kong Cable TV reporter and pulling him to the ground.

The reporter said he was assaulted after his crew refused to leave a media zone, Cable TV reported. They were seen surrounded by dozens of police.

Despite the problems, an Olympic official said the start of the sale went well. "There were so many people who wanted tickets so we decided to open more ticket windows. In general, so far the ticket sale has gone smoothly," said Sun Weide, spokesman for Beijing's Olympic organising committee.