Britain's top civil servant has intervened in the Priti Patel "bullying" row to demand a halt to the "unattributable briefings" that are "besmirching" the Government's reputation.

In a rare email to the UK's 430,000 civil servants, Sir Mark Sedwill warned that leaks about "tensions within Whitehall" were a "distraction".

He called for a return to "candour, confidentiality and courtesy" between ministers, special advisers and officials.

The move follows days of briefing and counter-briefing after unnamed Home Office sources accused Ms Patel of bullying officials – claims that were strongly refuted – and her permanent secretary, Sir Philip Rutnam, was criticised for "obstructing" and "undermining" successive Home Secretaries.

It will also be seen as a rebuke to Boris Johnson's chief adviser, Dominic Cummings, and his allies after a series of briefings attacking civil servants and rows over the alleged bullying of special advisers.