Priti Patel has been cleared of bullying members of her staff after an official investigation by the Cabinet Secretary.

The review, ordered by Boris Johnson, is believed to have found “no evidence” to support allegations that she bullied staff at the Home Office, Department for Work and Pensions (DWP) and Department for International Trade or that she breached the ministerial code by doing so.

The report by Sir Mark Sedwill was completed within the last week and has been presented to Mr Johnson on his return to Downing Street on Monday after his recovery from coronavirus.

“They have looked at all the claims and found nothing,” said a Whitehall source. “They trawled through lots of material but found no evidence.”

Sir Iain Duncan Smith, the former Conservative leader, said he had told the inquiry that there was no truth in the allegations of bullying when he worked with her at the DWP. 'I was categoric in the inquiry that there was no allegation against her, nor was she investigated at the time,' he said.

He urged the Government to investigate why the Home Secretary had been subjected to such allegations.

The findings are expected to be announced later this week although it is not thought likely that the full report prepared for the Prime Minister will be made public.

It comes only days after Sir Philip Rutnam, the former Home Office Permanent Secretary, formally launched his legal action against Priti Patel claiming “constructive dismissal”.

Sir Philip submitted his claim to an employment tribunal last Monday after resigning and accusing Ms Patel of bullying staff. He claimed he had been the victim of a "vicious and orchestrated" briefing campaign.

The row made headlines last month with the Prime Minister publicly defending her in the Commons, saying he would “stick with Prit.”

“The Home Secretary is doing an outstanding job - delivering change, putting police on the streets, cutting crime and delivering a new immigration system - and I'm sticking by her,” Mr Johnson told MPs.

It followed claims that officials in her private office at the Department for International Development had made a 'tsunami' of complaints about her behaviour. She was accused of ridiculing and belittling staff, and exerting 'heavy pressure' in emails.

There were also allegations that one member of staff at the Department for Work and Pensions (DWP) had taken an overdose after clashing with her, a charge dismissed by her allies as “ludricous.”

The claimant had only worked for her for two weeks, was in the process of leaving and had made the allegations of bullying against the department rather than her, according to her supporters.

In an email to Home Office staff last month, Ms Patel said she regretted Sir Philip's resignation.

She thanked him for his service but said it was "now time for the Home Office to come together as one team".

She said she "deeply cared" about the "wellbeing" of her civil servants and valued their professionalism.

The Cabinet Office said the process was still ongoing and final decisions on the report had yet to be made.