They are now investigating “serious allegations” against the Detainee Support & Help Unit, a London-based charity that has been granted £380,000 of lottery cash in recent years.

It is alleged that Comfort Afolabi, the 48-year-old head of the charity, put an undercover reporter posing as an asylum seeker in touch with an immigration fraudster who was selling fake passports.

The Big Lottery Fund, which distributes £600m a year to good causes, has suspended the charity’s latest grant of £200,000, which was awarded in March.

In a statement, the Big Lottery Fund said: “We have with immediate effect frozen the grant to DSHU and have begun an internal investigation into the organisation concerned.” It estimates £130,000 of the grant has not yet been handed over.

The Charity Commission said it, too, had received the allegations and had opened an “evaluation” that could lead to a full-scale inquiry.

The DSHU, which is based in Camberwell, south London, offers help to refugees and asylum seekers, particularly women with children, based in detention centres in and around the capital. It was approached by a reporter from BBC Radio Five Live who was posing as an asylum seeker.

According to the BBC, the head of the charity allegedly told the reporter: “This man can help you get a job and he can help you get documents,” before handing over contact details and quoting a price of £1,000 for a fake passport.

Yesterday Afolabi said she was innocent of any wrong- doing and would be consulting her lawyer. “The man [from the BBC] said he needed a job because his wife had died and he needed to send money to his children. I gave him a telephone number for an agency. That was all,” she said. “They want to damage me, they want to destroy me, maybe because I am black and because I am an activist.”

It has emerged separately that Afolabi was warned earlier this year by the charity’s independent examiner, the chartered accountants Samuelsons & Co, to improve its book-keeping.

According to material published by the charity, Afolabi, who now has indefinite leave to stay in Britain, took up her post because of her experience of being held for four months at Campsfield detention centre in Oxfordshire.

Afolabi, a Nigerian mother of five who has lived in Britain for more than 20 years, set up the group in 1997. It was given charitable status in 1999.

She wrote that immigration officials seized her on her return from Nigeria. “The conditions of a prisoner is [sic] by far better than those of a detainee. Whereas a prisoner has a term to serve and can look forward to his freedom, a detainee lives on fear, day in day out. The trauma of having no contact with my children was torturing me.

“I discovered that the state does not provide for the children or property of a detainee. That’s why I pledged to campaign for the alleviation of detainees’ suffering.”

Previous lottery controversies have led to a drop in ticket sales even though Camelot, its operator, has no say in the award of money to charities.

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