Charity Commission investigates bullying charity

Christine Pratt's charity helpline has been under intense scrutiny

The Charity Commission has begun an investigation into the charity at the centre of a row over claims of bullying at Downing Street.

It said it had begun an inquiry after receiving more than 160 complaints about the National Bullying Helpline.

Helpline chief executive Christine Pratt was criticised for saying it had been contacted by Downing Street staff.

She spoke out following claims in a book about Gordon Brown's temper and behaviour towards staff.

The Charity Commission said it had a duty to "promote public trust and confidence in charities, and is aware of the potential impact on other charities that run confidential help lines".

'Prepared to resign'

All four of the charity's patrons resigned and another bullying charity had strongly criticised Mrs Pratt for what they called a breach of confidentiality. She said she had not named names or revealed details.

The National Bullying Helpline was temporarily suspended on Wednesday, saying it was considering its future and Mrs Pratt was "prepared to resign if necessary".

The row began on Sunday with a story in the Observer - based on a book by journalist Andrew Rawnsley - alleging that Mr Brown grabbed staff by the lapels, shoved them aside and shouted at them.

Business Secretary Lord Mandelson denied the claims, insisting the PM was "demanding" but "doesn't bully people".

But Mrs Pratt then contacted the BBC to say a flat denial sent out the wrong message and she would expect Downing Street to follow "due process" and look into calls that her helpline had taken from a small number of staff.

She was criticised by Lord Mandelson who suggested her remarks were part of a "political operation" directed by the Conservatives.

The Tories accused him of trying to "smear" Mrs Pratt. Mrs Pratt has denied any political influence and it is understood is now being represented by publicist Max Clifford.

The government has denied allegations in Mr Rawnsley's book that the head of the civil service, Sir Gus O'Donnell, had a "pep talk" with Mr Brown about his behaviour towards staff following reports some were frightened by his temper.

Sir Gus said on Wednesday he had spoken to the PM about how to motivate staff but denied talking to him about his "behaviour".

Mr Brown has said claims he intimidated staff were "completely wrong".