A spiritual leader who was due to lead a 1,500-strong yoga class has been stopped from entering the country, his supporters said.
Swami Ramdevji, 47, was expected to lead the class in Glasgow on Monday night.
But his supporters said he was stopped at Heathrow Airport last night and detained for eight hours.
Ramdevji, who is also known as Baba Ramdev and reportedly has an 85 million strong worldwide following, was given a 24-hour visa and instructed to return to Terminal Five this afternoon, when his supporters fear he will be thrown out of the country.
The organisers of his visit said they have contacted Hindu temples throughout the UK asking for supporters to protest at the airport against the move.
A trust run by Ramdevji, who has his own television channel in India, bought the island of Little Cumbrae just off the coast of Largs in south west Scotland and established it as a yogacentre two years ago.
A Home Office spokeswoman said: "We would not comment on individual cases."
Media reports in India said Ramdevji was detained because he arrived at Heathrow on a visitor's visa instead of a business visa.
His spokesman SK Tejarawala was reported as saying: "It was not clear why the yoga guru was detained for over six hours at Heathrow. He was not carrying anything with him except a small bag of personal effects.
"It is for the British authorities to explain why he was detained."
Scores of supporters attended Terminal 5 this afternoon as the guru was expected to arrive.
They said he was given no explanation for his detention yesterday and claimed he could have been targeted by the Indian authorities for speaking out about corruption back home.
Omparkash Yadav, a group organiser who the guru stays with sometimes, said: "They didn't ask him any questions at all for six hours, then they looked at some his stuff, some papers he had written notes on.
"They kept those and his passport.
"It is not an issue with his visa, that was given by the British High Commission within four days.
"He has been here six or seven times before.
"The first time in 2006 he was a guest of the Queen at Buckingham Palace and the second time he was a guest of Tony Blair at the House of Commons.
"There has never been a problem before.
"He talks about corruption.
"The people are suffering.
"But the people are with him.
"That's the concern with government.
"They will try their best to bring him down."
Keith Vaz, Leicester East MP and chairman of the Home Affairs select committee, arrived at the airport holding hands with the guru who was mobbed by more than 150 supporters.
In the melee the Baba, dressed in sandals and an orange robe, nearly lost his clothing.
He addressed the throng in Hindi before he and Mr Vaz met the chief immigration official.
Mr Vaz said: "What has happened is not acceptable.
"No reason was given for him being held but we will find out what happened."