No 10 has said claims of routine bad behaviour to staff, including junior civil servants, were a malicious falsehood.

LONDON: David Cameron today called for an inquiry into allegations that Gordon Brown bullied staff at Downing Street.

The Conservative leader said that Sir Philip Mawer, Downing Street’s independent adviser on ministerial standards, should look into the allegations made by the Observer journalist Andrew Rawnsley and subsequently amplified by the National Bullying Helpline charity.

However, the NBH was dealt a blow today when one of its patrons resigned in protest at its decision to publicise allegations relating to No 10.

Referring to the allegations against Brown, Cameron said: “These are very serious matters. I’m sure that No 10 Downing Street and the civil service in some way will want to have some sort of inquiry to get to the bottom of what has happened here.

“One way for that to happen is for Sir Philip Mawer, who is in charge of policing the ministerial code, to be asked to look into this and to find out what has been happening and get to the bottom of it.”

Nick Clegg, the Liberal Democrat leader, also said the allegations needed to be investigated. “I do think this does need to be cleared up by No 10 as quickly as possible,” Clegg told BBC Radio 4′s Today programme this morning. “Bullying is wrong. It is totally out of order in whatever walk of life you work, however important you are.”

But Brown’s allies rallied to his defence. Lord Mandelson, the business secretary, said the government had more important things to do than investigate unfounded claims.

“If you think we are going to spend our time chasing around newspapers that want to splash on to their front pages allegations of this kind, just because they are relaunching and want to get the maximum publicity for what they are doing, books that need to be sold by their authors, every Tom, Dick or Harry who wants to jump up guided or otherwise by some Tory party press officer in order to pursue some smear or innuendo against the government – let me tell you, we’ve got better things to do in our lives.”

People making allegations about Brown’s behaviour needed to “put up or shut up”, Mandelson said. “We need some evidence to back up this sort of claim. We haven’t seen it.”

The prime minister’s spokesman restated cabinet secretary Sir Gus O’Donnell’s denials that he had launched an investigation into allegations of bullying by the prime minister or had issued him with a verbal warning.

But he declined to go into further detail about whether O’Donnell had ever mentioned Brown’s behaviour towards staff in private conversations. “They have lots of discussions about lots of things,” he said.

Brown also received support from a more unlikely quarter when Peter Watt, the former Labour general secretary, insisted that the prime minister’s behaviour under pressure fell short of bullying.

Watt, who was critical of Brown in his recently published memoirs Inside Out: My Story of Betrayal and Cowardice at the Heart of New Labour, said that the prime minister’s temper surfaced when he was under pressure, while at other times he could be a very supportive and loyal colleague.

“I think the term ‘bullying’ is a little bit emotive and possibly a little bit strong,” said Watt.

O’Donnell has been urged to launch a formal investigation into the bullying allegations, which were published in the Observer yesterday. The paper is serialising a book by Andrew Rawnsley that claims Brown swore at staff, grabbed them by lapels and shouted at them. Rawnsley also claimed O’Donnell had warned Brown to change his behaviour.

The Observer allegations became more damaging to Brown yesterday afternoon when Christine Pratt, the director of the National Bullying Helpline, said she had received calls from people working in Downing Street.

But today Professor Cary Cooper, an expert on workplace stress, said he was resigning from the NBH because he thought that Pratt had “breached confidentiality” by making such a statement.

“One of the things that is really important for any helpline or any counselling service is to retain confidentiality of the people calling up,” Cooper said.

The NBH went public after Mandelson flatly denied the Observer claims, insisting that Brown was simply “demanding”, “emotional, “and had a degree of impatience”.

Pratt said yesterday: “We are not suggesting he is a bully. What we are saying is there are people in his office working directly with him that have issues and concerns, and have contacted our helpline. We believe the present statement put out by Lord Mandelson is a nonsense and non-credible.”

Anne Snelgrove, a Labour MP and Brown’s parliamentary private secretary, said today that she had cut links with the NBH some time ago after hearing serious allegations – which she could not substantiate – about the charity, which revealed yesterday that it had received complaints from people working at No 10.

She told the Today programme that she used to support the charity in her capacity as a local MP but that she withdrew her support after Pratt refused to meet her to discuss serious allegations that had been made against the charity. Snelgrove did not spell out what the allegations were, but the Today programme said that one involved a caller to the helpline being offered a commercial service.

Pratt told the programme that the helpline did offer callers the option of being referred to dispute resolution providers, one of which was run by herself and her husband. She said this arrangement was sanctioned by the Law Society. She also said that she had been willing to discuss this with Snelgrove provided that trustees from the charity were present.

Pratt also denied breaching confidentiality when she decided to speak out yesterday.

The Swindon-based National Bullying Helpline was set up in 1997 and insisted it was not political nor seeking publicity. The Conservative MP Ann Widdecombe is its patron and it quotes support from David Cameron on its website, and has another Conservative patron, councillor Mary O’Connor. But Widdecombe defended the organisation as “utterly non-political”.

However, government sources questioned the charity’s credentials, suggesting it had made no contact with No 10 and operated only two doors away from the local Conservative party.

In another BBC interview today, Pratt said that the Conservative party had been in touch with her about her allegations. But she said that was “irrelevant” to her decision to speak out.

“Yes. I have been in touch with them, they have been in contact with us but we are not a political charity, I’m not politically motivated,” Pratt said.

She added: “We received a call of support from local MPs but that is irrelevant.”

Pratt told the Today programme that the NBH had received two calls from the deputy prime minister’s office and two or more from the prime minister’s office. Asked if any of the callers had described Brown as a bully, Pratt said: “Absolutely not. Nor have we said that Gordon Brown is a bully. Our concern here is the public statement from No 10 of denial.”

Brown should have promised to look into the allegations, in line with the established code of conduct, Pratt said.