John Bercow, the former Commons Speaker, has “categorically” denied having ever bullied anyone.
Lord Lisvane, the former Clerk of the House, confirmed on Thursday he had made a formal complaint about Bercow’s behaviour.
The Times reported Lisvane, who served as Bercow’s most senior official, had handed a dossier of allegations to the parliamentary commissioner for standards.
Outgoing Labour leader Jeremy Corbyn has reportedly been lining up Bercow, who was a Tory MP before becoming speaker, for a peerage.
In a statement, Bercow said that since retiring it had “become increasingly obvious that the government has no intention of honouring the centuries-old convention that a departing speaker is promptly elevated to the House of Lords”.
He added: “Indeed, it has been suggested to me that the government actively seeks to block any other attempt to nominate me for membership of the upper House.
“I have seen in the media that Lord Lisvane is formally complaining that I bullied staff. For the record, I categorically deny that I have ever bullied anyone, anywhere at any time.”
There have been suggestions that Downing Street could hamper the move, with the prime minister’s official spokesman highlighting a “long-standing convention” that opposition leaders nominate individuals form their own parties.
Downing Street said today the allegations against Bercow were “very concerning” and should be “investigated thoroughly”.
No.10 said it was “important” the parliamentary leadership responds “fully and promptly to any concerns which are raised”.
The prime minister’s official spokesman said: “These are very concerning allegations and they need to be investigated thoroughly.
“Everyone working in parliament deserves to be treated with dignity and respect.”
Business secretary Andrea Leadsom said the complaint, if it is upheld, should have an “impact” on whether he is made a peer.
Leadsom, who as leader of the Commons clashed repeatedly with Bercow, told Sky News that the complaints procedures for parliamentary staff – which she helped establish – applied to everyone in the Commons.
“The whole purpose of that was that anybody, including the speaker of the House of Commons whoever he or she may be, should also be subject to that procedure,” she said.
“In the event that there are genuine, upheld complaints about any persons that should have an impact on whether they are found suitable for the House of Lords.”
The document is said to accuse Bercow of having bullied and humiliated staff, including using inappropriate language.
Bercow has consistently denied allegations of bullying from former members of staff in the past.
In a statement on Thursday, he said: “During the five years that we worked together, Lord Lisvane had ample opportunity to raise any accusations of bullying with me.
“At no stage did he do so, even though he became Clerk of the House – the most senior official. The timing of this intervention is curious.”
Bercow left the speaker’s chair on October 31 and has been replaced by Sir Lindsay Hoyle.