The roughing up and brief detention of a British journalist by Chinese police this morning has been described by Tessa Jowell as an ugly incident and a breach of promises of media freedom.

John Ray, the China correspondent for Independent Television News (ITN), was grabbed by police and forced to the ground as he tried to report on a protest just half a mile from the Bird’s Nest Olympic stadium by a group of foreign activists demanding freedom for Tibet. He was dragged along the ground, spreadeagled and his hands stamped on.

Police ignored his cries that he was a journalist. In a brief telephone call with friends while in detention, he said: “I’ve been roughed up. They dragged me, pulled me and knocked me to the ground.” He said he was being filmed by the police and was then ordered to hang up.

He was hauled into a nearby restaurant, passing startled lunchtime diners, forced down on a sofa and his arms held down at his sides. "They made 'T' signs and one of them asked me for my views on Tibet. I said I was a journalist and had no views on Tibet." His shoes were pulled off, apparently to prevent him from trying to escape.

The police would not allow him to put his hands in his pockets so that he could show them his official accreditation papers. He tried to run away and was released only after officers finally permitted him to show them his identity papers. He said that he had been shaken but was only slightly hurt.

However, the incident raised fresh doubts about China's willingness to allow free coverage of the Games. Mr Ray said: "I wonder how this fits in with their solemn promise to allow free and unrestricted reporting during the Olympics."

Ms Jowell, Britain's Olympics minister, called on the Chinese organisers to honour the commitments they made to the International Olympic Committee (IOC) when Beijing was awarded the Games.

“This was clearly a very ugly incident and is completely in contradiction to the assurances that the Chinese made about media freedom during the Olympics," she told The Times. "I sincerely hope that it is not repeated and that the guarantees made will be consistently respected." She has made a point of raising the subject of media freedom during regular exchanges with the Beijing Olympic Organising Committee.

The IOC said that it was investigating and would raise its concerns with the appropriate authority if necessary. Kevin Gosper, the Australian chairman of the IOC's press commission, said: "We are very serious about the issue and are concerned that the media must be free to report on the Olympic Games. We need to get the full facts."

Such heavy-handed treatment of foreign journalists is relatively unusual in China — especially in Beijing.

ITN said: “We intend to protest in the strongest possible terms to the Chinese authorities and to seek assurances that the treatment meted out to Mr Ray will not be repeated.”

A Chinese passerby told The Times: "What I saw is the security guards were very rude to the reporters. They pushed them. I heard orders being shouted by the officers. 'Just use your hands,' they said. 'Get to the reporters and cover their camera lenses'. As a Chinese person I feel bad."

The guards tried to cover the lens of Times photographer David Bebber as one of the pro-Tibet protesters was driven away. She had come out of the small thatched security hut at the end of the row of shops and made a T sign before she was put into a car and driven away.

Jonathan Watts, president of the Foreign Correspondents' Club of China, said that the organisation was appalled. “We call on the authorities to return his equipment, apologise, and investigate potential illegal action or abuse of authority by police."

Police took barely a minute to detain the protesters from Students for a Free Tibet. Two members of the activist group who waved a "Free Tibet" banner from a bridge outside the Chinese Ethnic Culture Park were detained before they could even unfurl the banned Tibetan Snow Lion flag.

Another six dressed in “Free Tibet” T-shirts and shouting slogans had handcuffed themselves to each other and to bicycles at the front gate of the park. They were swiftly rounded up and taken away by police.

The group has tried to stage several protests coinciding with the Olympics in Beijing to publicise their demands for freedom for the Buddhist Himalayan region.

China is particularly sensitive to any attempts to demand independence for Tibet, especially since a riot in early March in Lhasa when angry Tibetans rampaged through the streets, setting fire to shops and offices and killing about 22 people, mostly ethnic Han Chinese.

Police usually deport swiftly any foreign activists who try to raise the issue of Tibet. Several have already been expelled in the past week.