DOMINIC RAAB was so “demeaning and abrasive” to junior colleagues that many were “scared” to enter his office, the top civil servant under the then-foreign secretary alleged today.

Lord McDonald said he raised his concerns to Cabinet Office investigators at the time and urged Prime Minister Rishi Sunak to “have another look” at bullying complaints procedures.

The PM made Mr Raab his deputy and Justice Secretary when he entered No 10.

FDA union head Dave Penman called on Mr Sunak to reform the complaints system to help address a “toxic work culture” in Whitehall.

In a letter, Mr Penman urged the PM to appoint a new independent adviser on ministers’ interests.

The post has been vacant since Lord Geidt quit in June.

“As we have seen over the last few weeks, there is increasing scrutiny over the conduct of ministers and, in particular, accusations of bullying, behaviour that has no place in a modern workplace,” it said.

Lord McDonald, who was the Foreign Office’s permanent secretary when Mr Raab led the department, said the minister “couldn’t be made to see” the impact he was having on staff.

“Colleagues did not complain to me formally, it was kind of their professional pride to cope, but many were scared to go into his office,” he said.

Deputy Labour leader Angela Rayner demanded an independent investigation into Mr Raab.

“Rishi Sunak clearly knew about Dominic Raab’s reputation when he reappointed him to his Cabinet,” she said.

Despite the warnings, the PM stood by Mr Raab today.

Mr Sunak continued to insist he is not aware of “any formal complaint” about Mr Raab’s behaviour and urged anyone with concerns to come forward.

Mr Raab’s spokesman said: “Dominic has acted with professionalism and integrity in all of his government roles.”