The widow of entertainer Roy Castle has accused the trustees of the fund set up in his name of mismanagement.

The Roy Castle Lung Cancer Foundation was set up in 1994 to raise money for research into lung cancer, the condition that killed him.

It has raised £13m, but in October last year the trustees called in accountants following allegations of financial irregularities involving an employee. One member of staff resigned at the time.

Fiona Castle's comments, to be aired in a television interview on Thursday night, came as the Charity Commission confirmed it had launched an official investigation into alleged financial irregularities.

A spokesman for the commission, Nicholas Fearon, said the trustees had approached them with their concerns about alleged irregularities involving expenses claims.

An independent auditor was sent in to look at the foundation's books and his report has been forwarded to the commission.

Mr Fearon said: "We are not a prosecuting authority but if we come across any criminal activities we will pass it on to the police."

Mrs Castle told ITV's Tonight With Trevor McDonald: "Roy could not tolerate anything that was untoward. He was a down-to-earth, little Yorkshireman."

She said he would not have tolerated mismanagement and added: "He would have said 'Forget it. Take my name off it.'

"I was very tempted to do that on his behalf initially but then I had to think of the purpose of it which is that 40,000 people a year are dying of lung cancer and we have to do something to help them."

The Tonight programme says a large percentage of the £13m has been spent on fund-raising and administration instead of medical research.

In her interview with Sir Trevor McDonald, Mrs Castle says the latest developments may jeopardise the foundation that bears her husband's name.

'Tarnished image'

She said: "I'm very fearful that recent events have taken the future away from the organisation.

"Certainly it has tarnished the image and who know what is going to happen from here on."

Foundation spokesman Mike Birkett said the sums involved were "not large" and he stressed that they were co-operating fully with the commission.

He said there was no question of Mrs Castle removing her husband's name from the foundation.

He told BBC News Online: "It won't come to that. Fiona is still actively promoting the foundation and is not distancing herself."

He added: "We have spoken to her this week and she has accepted doing personal appearances, in fact she opened our new shop in Ripon (North Yorkshire)."