Labour has been accused of coordinating bullying allegations against Priti Patel after Jeremy Corbyn revealed that civil servants had made complaints to the party.

As Boris Johnson declared in the Commons that he was "sticking by" his "outstanding" Home Secretary, Tory allies of Ms Patel accused civil servants of undermining their impartiality with politically-motivated moves and called on the Cabinet Secretary to investigate.

Ms Patel is said to be facing a "tsunami" of allegations that she bullied staff at the three departments where she has been a minister: the Home Office, the Department of Work and Pensions and the Department for International Development (Dfid).

In one case, she is alleged to have bullied a civil servant out of his job at Dfid so badly that he signed off with stress.

Sir Mark Sedwill, the Cabinet Secretary, is investigating "to establish the facts" over the claims after Ms Patel's top civil servant, Sir Philip Rutnam, resigned, accusing her of bullying.

Mr Corbyn's spokesman said civil servants had contacted his office directly with bullying claims. "They build up the picture that has already accumulated in recent days. It is quite clear this is not an isolated allegation by one individual about one incident or one set of incidents," he said.