China's government on Thursday moved to head off nationwide protests targeting French retailer Carrefour as it sought to rein in what state media described as "excessive displays of patriotism" that risk damaging the country's image before the Beijing Olympics.

Protests ranging in size from a dozen people to a few hundred did break out in at least five regional Chinese cities, according to the state-run Xinhua news agency, but police quickly dispersed or detained those involved.

In Beijing on Thursday, a heavy uniformed and undercover police presence deterred most protesters at the branch of Carrefour closest to the university district.

Over the course of the morning a handful of young people wearing t-shirts with slogans decrying the Tibetan independence movement and the western media were quickly detained by police and made to take off their shirts.

The latest outburst came as Mia Farrow, the American actress and human rights campaigner, was allowed to enter Hong Kong to give a speech criticizing China's relations with Sudan. Her visit is seen by many as a test of how free the city dared to be while hosting the torch, and follows the deportation of several activists in the past few days.

Popular anger towards the west and its media outlets has exploded in China in recent weeks in reaction to protests along the route of the Olympic torch relay, which is due to continue through the streets of Hong Kong today.

Pro-Tibetan demonstrations in Paris, where one protester tried to snatch the torch from a Chinese para-Olympian in a wheelchair, provoked the most heated response, while CNN has borne the brunt of anti-western media attacks after a commentator referred to the Chinese government as "goons and thugs".

In the southern city of Changsha on Thursday around 200 protesters carrying national flags and banners saying "support Olympics", "Oppose Tibet Independence", "Love China" and "Unity is Power" gathered outside the entrance of a Carrefour outlet and tried to persuade people not to shop there, according to Xinhua.

Small protests also occurred in the cities of Fuzhou, Xi'an, Shenyang and Chongqing, but were dispersed and "no conflicts occurred", Xinhua said. Protests outside Carrefour stores in regional centres in recent weeks have been much larger and more unruly.

A boycott due to coincide with the May 1 national holiday appeared to have mostly failed at Carrefour stores in Beijing, where staff said business was slightly slower than could be expected for a holiday but nonetheless busier than normal.

Carrefour refused to comment on whether calls for a boycott had affected the chain's business. The retailer has 112 stores across China and employs more than 44,000 people.

After initially tolerating anti-western protests the government has mobilised its state security apparatus to quell excessive outbursts of nationalist fervour.

In recent days all internet searches for Carrefour's name in Chinese have been blocked by the government.

In comments posted on an internet forum a student from Beijing Union University who was part of a planning committee for today's protests described an encounter with two plain-clothed public security officers at a committee meeting in a KFC restaurant earlier this week.

The officers forbade the students from organising protests or wearing clothes with printed slogans and eventually the students agreed to call off their activities.

"We were curious how they found out about us … [But] they said that if we had some special topics in our [online] conversations, they were supposed to know," the anonymous author of the post said.

• Reuters reported on Thursday that climbers taking a special Olympic torch up Mount Everest had been held up at advanced base camp, awaiting better weather before heading to the world's highest peak, a Beijing official said.

Sun Bin, Everest project manager at the Beijing Organising Committee for the Olympic Games, said climbers had reached the camp at around 6,500 metres (21,300 feet), but the wind would have to die down before an attempt was made to scale the remaining 2,348 metres (7,700 feet).

"Normally there is a three to four day window of good weather in the first week of May," he said . "We want to try to catch this window to try and summit."

China moved to head off nationwide protests against the French retailer Carrefour on Thursday, fearing that they threatened to damage the country's image ahead of the Beijing Olympics.

Small groups of up to a few hundred people staged protests in at least five Chinese cities, according to the state-run Xinhua news agency. Police quickly dispersed or detained those involved.

In Beijing, a heavy uniformed and undercover police presence deterred most protesters at the branch of Carrefour closest to the university district.

During the morning a few young people wearing T-shirts with slogans decrying the Tibetan independence movement and the western media were detained by police and made to remove their shirts.

The latest outburst of nationalist fervour came as Mia Farrow, the US actress and human rights campaigner, was allowed to enter Hong Kong to give a speech criticising China's relations with Sudan.

Her visit was closely watched as a test of how open the city dared to be while hosting the Olympic torch, and follows the deportations of several activists in the past few days.

Popular anger towards the west and its media has grown in China in recent weeks in reaction to anti-China protests during the Olympic torch relay in Europe and the US.

Pro-Tibetan demonstrations in Paris, where one protester tried to snatch the torch from a Chinese para­lympian in a wheelchair, provoked the most heated response, while CNN has borne the brunt of anti-western media attacks after a commentator referred to the Chinese government as "goons and thugs".

A boycott due to coincide with the May 1 national holiday appeared to have failed at Carrefour shops in Beijing. Staff said business was slightly slower than expected for a holiday but was nonetheless busier than normal.

Carrefour refused to comment on whether calls for a boycott had affected its business. The retailer has 112 supermarkets in China and employs more than 44,000 people.

After initially tolerating anti-western protests, the government has used its state security apparatus to quell protests. In recent days the government has blocked all internet searches for Carrefour's name in Chinese.

● Reuters reported a Beijing official as saying that climbers taking a special Olympic torch up Mount Everest had been delayed at Advanced Base Camp while they awaited better weather before heading to the peak.