It comes after four women alleged in a joint investigation by The Sunday Times, The Times and Channel 4 Dispatches that the comedian and presenter sexually assaulted them between 2006 and 2013.

A report, released by Channel 4 on Thursday, said the investigation "found no evidence to suggest that there was knowledge within the channel of the allegations contained in the Dispatches programme about Russell Brand's behaviour" while he was a presenter on two programmes between 2004 and 2007.

However, it did say an allegation made in 2009 by a staff member which concerned the comedian's conduct towards them was "not passed up Channel 4's senior management chain" nor investigated at the time as it ought to have been.

"Channel 4 has apologised to the former Channel 4 staff member for the breakdown in 2009, communication delays in 2023 and the distress this matter has caused," the report said.

Mr Brand, 48, has repeatedly denied the allegations against him and said his relationships were "always consensual".

The investigation also said it found "no written or corroborated evidence to show that suspicions of serious allegations about Brand's behaviour were held within the channel" before a charity episode of The Great British Bake Off was broadcast in 2019 - the same year the Dispatches programme was commissioned.

The Stand Up To Cancer celebrity special was filmed in 2018, but the investigation found that there was "no record of concerns being raised within Channel 4, or in public" when Mr Brand was given the job or after the episode was broadcast.

The report said "extensive changes" to the broadcaster's management and commissioning teams have been made since the alleged incidents took place.

It said: "Today, rigorous safeguarding policies and whistleblowing support ensures staff and suppliers can report concerns anonymously and confidentiality."

'A matter of regret'

Alex Mahon, Channel 4's chief executive, said it was a "matter of regret" for the industry that "repugnant behaviours were tolerated - and indeed appeared on-air - in the past".

She added: "Production staff, employees and suppliers should never experience inappropriate behaviour. Channel 4 and I are committed to creating an environment where if any employee or person working on a Channel 4-commissioned show feels uncomfortable about behaviour towards them, then processes are in place for investigation and for appropriate action to be taken."

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A statement by Channel 4 chair, Sir Ian Cheshire, said: "The board is satisfied that no Channel 4 employees were aware of the deeply disturbing alleged behaviour contained in Russell Brand: In Plain Sight: Dispatches.

"However, we consider it clear that a serious allegation about Russell Brand was made in 2009 by a then-serving member of staff which was not properly investigated nor escalated to Channel 4's then-senior management.

"The board and ethics committee are confident that strengthened safeguarding processes introduced in the past decade mean that an allegation such as this would today be reportable through multiple routes.

"The investigation's recommendations, which are accepted in full, will further strengthen Channel 4's already rigorous safeguarding processes to further protect and uphold the welfare of all employees and those that the channel works with."