The head of the police watchdog has been forced to resign after becoming the subject of a police investigation, Home Secretary Suella Braverman says.

Independent Office for Police Conduct director general Michael Lockwood said on Friday that he was resigning for “personal and domestic reasons”.

But on Saturday the home secretary said she had taken action after learning of the probe into a historical allegation.

Mr Lockwood was asked to either resign or be suspended, Ms Braverman said.

She said she had accepted the resignation, which came into immediate effect. No further information about the nature of the allegation was given.

Home Office staff are now working with the IOPC to “put in place temporary arrangements for the organisation’s leadership”, Ms Braverman added.

The home secretary said in a statement: “I took immediate action upon being made aware that Mr Lockwood was the subject of a police investigation… and instructed my officials to ask him to resign or face immediate suspension from his role.”

Mr Lockwood was the first person appointed to lead the IOPC when it replaced the Independent Police Complaints Commission in 2018.

It handles the most serious complaints against police in England and Wales.

In his statement on Friday, Mr Lockwood said he was resigning with “great sadness”, adding that it had been an “enormous privilege” to serve as the organisation’s first director general.

He was previously chief executive of the London Borough of Harrow, north-west London.

After the Grenfell Tower fire in 2017, Mr Lockwood was asked by a government task force to lead the recovery and remediation work and liaise with the bereaved families and survivors, according to the IOPC website.

A qualified accountant, he has also worked in central government at the National Audit Office, and for the Local Government Association as executive director for local government finance and policy.