Dominic Raab faced fresh questions on Saturday, after it was reported that his refusal to speak to Foreign Office staff he viewed as “time-wasters” caused a “blockage” during the evacuation from Afghanistan last year.

The Deputy Prime Minister, whose oversight of the evacuation amid the Taliban’s power-grab came in for heavy criticism, was the subject of a fresh report in The Guardian newspaper which reported on claims that his working relationship with officials had a negative impact on Foreign Office efforts.

Mr Raab is facing an investigation into his conduct, after the Prime Minister agreed to open an independent investigation into the Justice Secretary on his request after two formal complaints were made against him.

Mr Raab is understood to deny the latest claims, which suggest that ahead of the final stages of the UK withdrawal some decisions were “delayed and backed up” as the then-foreign secretary allowed only a small number of senior staff to engage with him and his private office.

According to the report, he described some senior Foreign Office officials as “time wasters”.

One source told The Guardian that quick decisions were needed but “we couldn’t get him to listen to this message, let alone act on it”.

They described the “blockage” as “very costly”.

Mr Raab told the Commons on Wednesday that he was “confident” he has behaved “professionally”, with Downing Street saying that Mr Sunak still has full confidence in his deputy.

Mr Raab has been facing a series of allegations he bullied officials and deployed rude and demeaning behaviour in previous Cabinet roles.

In a letter to Mr Raab on Wednesday, Mr Sunak told the Cabinet minister that “integrity, professionalism and accountability are core values of this Government” and said that an investigation was the “right course of action”.

In his letter to the Prime Minister, Mr Raab said: “I have just been notified that two separate complaints have formally been made against me, in parallel, from my time as foreign secretary and my first tenure as justice secretary, which ended in September of this year.

“I am, therefore, writing to request that you commission an independent investigation into the claims as soon as possible.

“I will co-operate fully and respect whatever outcome you decide.”

The Conservative MP for Esher and Walton told Mr Sunak he had “never tolerated bullying, and always sought to reinforce and empower the teams of civil servants working in my respective departments”.

Mr Raab’s later spell at the Ministry of Justice followed his demotion from foreign secretary in September last year, after widespread criticism of his handling of the Afghanistan crisis.

He was on holiday in Crete in August as the Taliban swept across the country and was seen relaxing on a beach on the Greek island as members of the militant group entered Kabul, although he insisted he was in touch with officials and ministerial colleagues.

Mr Raab is understood to reject the allegations, with it said that senior officials were responsible for the flow of information to him and he did not pick and choose who he wanted to hear from but rather followed the advice given to him.