Embattled Northern Ireland secretary Peter Mandelson did a frantic round of the TV studios last night, hoping to put to rest the rumours flying around regarding his role in the passport application for the Indian tycoon who gave one million pounds to the dome.

Mandelson confirmed that he had spoken - in person, rather than through officials - to a Home Office minister about British citizenship for Srichand Hinduja but denied any further involvement or having put pressure on the Home Office.

"My concern was to treat them [the brothers] courteously throughout without giving them any preferential or favourite treatment help at all. The facts speak for themselves. I acted in an entirely proper way", he said.

The prime minister's office support Mandelson, saying that he had done nothing improper.

However, the Tory chairman, Michael Ancram, said that for the second time in three years Mandelson had been shown to be "less than candid" in his dealings with colleagues.

Liberal Democrat MP Norman Baker, credited with exposing the issue, warned the prime minister that he would be "unwise" to give Mandelson a job should Labour win the next election.

Blair's official spokesman, Alistair Campbell, was forced into an unusual situation when he said that he had been wrong to tell reporters earlier in the week that Mandelson had not spoken to the Home Office himself when he said it was officials in his private office who had made the call.