Tony Blair and Gordon Brown mounted a diplomatic offensive to protect Britain’s reputation in India and the sub-continent yesterday as a television racism row grew into an international crisis.

India threatened to make a formal protest about the racist bullying of the Bollywood star Shilpa Shetty on the reality show Celebrity Big Brother.

Effigies of the show’s organisers were burnt and in Britain there were 22,000 complaints to Ofcom. The Channel 4 program had become the most complained about in the broadcasting watchdog’s history.

Brown, who is on his first visit to India, described the comments on the show as offensive and condemned anything that harmed Britain’s reputation as a tolerant country.

Blair said little initially. Questioned in the Commons, he said that MPs should oppose racism in all its forms. But after protests poured in he authorised a No. 10 statement saying that Britain would not tolerate racism in any way. His spokesman said: “What clearly is to be regretted and countered is if there is any perception abroad that in any way we tolerate racism in this country.

“What the response to the program has shown is precisely the opposite — that there is no level of toleration in this country for anything which, rightly or wrongly, is perceived to be racist. The message should go out loud and clear that we are a tolerant country and we will not tolerate racism in any way.”

The spokesman emphasised that Blair had not seen the programs.

Channel 4 claimed that the contested remarks were not racist but the result of a “cultural clash” between housemates. A spokesman said: “The nature of the show often includes incidents where conflicts arise and housemates are encouraged to resolve issues among themselves.”

Channel 4 promised to “step in” if it identified racist abuse within the house. The latest abuse of Shetty was on the front page of Indian newspapers and widely covered by radio and television news. Shetty’s mother told The Times that she was saddened at the distasteful treatment of her daughter by fellow contestants.

Sundanda Shetty described her 31-year-old daughter as a “strong kid” who would bounce back by handling the situation with dignity and adhering to the strong Indian family values with which she was brought up.

“We were saddened that she was crying on TV,” the elder Shetty said. “It is not a happy feeling to see your daughter crying. We have not seen that often in our home. She has always been loved and respected.”

At first the Chancellor — no fan of the program — was reluctant to be drawn in, but as the day wore on the situation worsened. The Indian Government said that it was preparing to make a formal complaint. Brown was warned that it could damage relations. Then he was mobbed by Indian journalists demanding a response. By the evening demonstrators in the city of Patna had burnt an effigy marked “Big Brother."

Three of Shetty’s housemates, including Jade Goody, her principal tormentor, are alleged to have taunted her because she is Indian, including making gibes about her cooking, suggesting that she was dirty, imitating her accent and asking whether she lived in a shack.

Shetty and Goody exchanged insults again last night after Goody accused Shetty of being a “princess” and thinking that she was better than others. Shetty replied: “Oh please, learn some manners. You know what you need? You need elocution classes, Jade.” Later, Goody said: “Go back to the slums and find out what real life is about lady.”

After an earlier noisy exchange, another housemate commiserated with Shetty, saying: “I don’t think there’s anything racist in it,” but Shetty replied: “It is, I’m telling you.”

Shetty will come head to head with Goody in this Friday’s public eviction vote.

Anand Sharma, India’s junior Minister for External Affairs, said: “The Government will take appropriate measures once it gets to know the full details. Racism has no place in a civilised society.”

Brown said: “I understand that in the U.K. there have already been 10,000 complaints from viewers about these remarks, which people see as rightly offensive. I want Britain to be seen as a country of fairness and tolerance. Anything that detracts from this, I condemn.”

Kamal Nath, India’s Trade Minister, told Brown that the program could lead to a diplomatic crisis, and Sir Michael Arthur, the British High Commissioner, who is accompanying the Chancellor, warned him privately that his three-day trip could be overshadowed by the affair. The tension could continue on Friday, when Brown is due to visit a Bollywood studio in Bombay.

Shetty is a household name in India, being one of Bollywood’s top stars. India has the biggest film industry in the world, and celebrities such as Shetty are worshipped by their fans.

The Times of India carried the story on its front page under the headline “Big(ot) Brother bullies Shilpa." It declared: “Shilpa Shetty has unwittingly become the symbol of officially multicultural Britain’s very public, sometimes two-faced, fight against racism.”

The Indian Express also ran the story on its front, under the headline “Racists target Shilpa Shetty." It said: “Bollywood actress Shilpa Shetty, participating in U.K.’s popular reality TV show Celebrity Big Brother, is allegedly the target of racist attacks.”

As well as complaints from the public, Hertfordshire police have started an inquiry — the programme is filmed at Elstree — and Carphone Warehouse, which sponsors the program, has threatened to withdraw support.

Shetty and the other contestants are unaware of the outside reaction. However, there could be an up side for Shetty. With a wave of public sympathy, William Hill, the bookmaker, has made her favorite to win.

Predictably, the controversy revived interest in a previously humdrum series. Tuesday’s highlights program averaged 4.5 million viewers, up from 3.5 million on Monday. The launch of the series attracted 7.3 million viewers.

The affair could have far-reaching ramifications for the state-owned broadcaster.

Andy Duncan, the Channel 4 chief executive, will deliver a speech to media regulators in Oxford today, warning them that the broadcaster’s future was in doubt. He is expected to call for a public subsidy to continue to produce innovative public service programming. The speech could not have come at a worse possible time.