Dominic Raab has said the “overwhelming majority” of his staff “relish” working on his “very ambitious agenda”.

The Deputy Prime Minister made the comments while the official inquiry into his behaviour continues.

Adam Tolley KC is investigating bullying claims and considering a number of formal complaints made by senior civil servants against Mr Raab, who is also Justice Secretary.

We are served by a terrific cohort of civil servants. By and large, the relationship is very effective with ministers across the board

Asked if anything was being done at the Ministry of Justice (MoJ) to improve staff morale and change culture, Mr Raab told the Lords Home Affairs and Justice Committee on Wednesday: “I’m not going to touch on anything which relates to the inquiry. I’m sure you would agree that would be improper of me.

“But let me say generally, both in previous departments but and in the Ministry of Justice, I would say we are served by a terrific cohort of civil servants. By and large, the relationship is very effective with ministers across the board.

“I think that we’ve also got a very ambitious agenda in the way that I described, and the overwhelming majority relish that …

“I work very closely with Antonia Romeo, my permanent secretary. We’ve got all the processes in place in relation to bullying processes and procedures to make sure that folk who want to make a complaint can, in the right way, it’s important that’s there.”

Labour peer Baroness Chakrabarti asked again specifically about Whitehall staff in his private office whether, while waiting for the inquiry to conclude, “in the interim, in the spirit of humility, have you reflected and done anything different – because it is a serious thing to be accused of – to perhaps change the dynamic in the department close to you with your close staff?”

To which Mr Raab replied: “So I think you’re now trying to take me into the inquiry which is improper and it’s got nothing to do with free speech and I’m going to leave it there.”

Boris Johnson reportedly privately warned Mr Raab about his conduct when he held several cabinet positions under the former prime minister and is understood to have given evidence to the inquiry, which could conclude within weeks.

Earlier this month, sources confirmed to the PA news agency that Mr Raab had been questioned as part of the probe.

Dozens of witnesses including top departmental civil servants are also believed to have spoken to the inquiry, which could determine his political fate.

Mr Raab has denied bullying and insisted he had “behaved professionally throughout” but said he would resign if an allegation of bullying was upheld.

Rishi Sunak resisted calls to suspend his deputy while under investigation but could face questions again about his knowledge of the allegations before bringing Mr Raab back into the Cabinet if the findings are damning.

Downing Street ruled out the Prime Minister being aware of “formal complaints”, but sources said he had been warned about his ally’s behaviour.

The eight formal complaints centre on Mr Raab’s tenures as foreign secretary, Brexit secretary and during his first stint as justice secretary.

Mr Raab ordered the investigation in November after coming under pressure following numerous claims, including that he was so demeaning to junior colleagues that many were “scared” to enter his office.