Police announced the investigation into allegations of fraud connected with the trust fund on Thursday.

Members of the Louise Woodward and Family Trust released a statement which read: "The terms of the appeal publicised in the news media and the appeal literature made it clear that the money raised by the appeal was to be used for the personal support of Louise and family and (among other things) to meet travelling and other expenses, living expenses both in the USA and in England.

It added: "It is understood that a member of the public has made a complaint to Cheshire Police in relation to allegations relating the existence and used of a forged invoice."

Nick Garnett reports from Manchester on the investigation

Woodward, 20, returned to the UK in June after Massachusetts' highest court upheld her manslaughter conviction for the death of eight-month-old Matthew Eappen.

Cheshire Police fraud squad officers have already interviewed several witnesses in the UK and the American FBI are involved in the inquiry.

The allegations are understood to relate to a £9,000 invoice submitted to the fund by Woodward's mother, Susan, for accommodation at the home of her daughter's American lawyer, Elaine Whitfield Sharp.

'False bill'

Ms Whitfield Sharp's husband, Dan, said that he and his wife, since sacked by the defence team over allegations that she told a police officer arresting her for drink driving that she no longer believed her client was innocent, provided free accommodation for Mrs Woodward while awaiting her daughter's trial.

He alleged Mrs Woodward then presented a false bill to the appeal fund for £9,113.50.

When the allegations first emerged earlier this year the fund trustees held an emergency meeting but continued to support the former au pair's parents, saying they believed they had always acted in "an honest and straightforward manner".

A spokesman for Cheshire Police said: "At the current time the inquiry has focused upon allegations relating to the existence and use of a forged invoice."

Appeal fund is under investigation

Dan Sharp said the FBI had already interviewed a number of people in the US "at the request of a UK law enforcement agency".

In October last year Louise Woodward was found guilty of the second degree murder of Matthew Eappen.

Her conviction was later reduced to manslaughter and her sentence reduced to the time she had already served.

In a statement, the trustees of The Louise Woodward and Family Trust said they had not yet been contacted by the police investigating the fraud allegation, but stressed they would be willing to co-operate with the inquiry if asked.

They said that the appeal publicised in the media made it clear that the money raised would be used for "the personal support of Louise and family for travelling, living, security and other expenses".

Further legal action

Woodward is also facing a possible multi-million pound award against her at a Boston court on Monday after a wrongful death suit was filed by Matthew Eappen's parents in June.

An award made in a United States court would not be enforceable while she remains in Britain.