BP CEO Bernard Looney has resigned after admitting that he had not been "fully transparent" about "historical relationships with colleagues," according to a statement from the oil giant on Tuesday.

Murray Auchincloss, the company's CFO, will act as CEO on an interim basis.

"In May 2022, the Board received and reviewed allegations, with the support of external legal counsel, relating to Mr Looney's conduct in respect of personal relationships with company colleagues. The information came from an anonymous source," the statement said. During that review, Looney disclosed "a small number of historical relationships with colleagues prior to becoming CEO," but no breach of the company's code of conduct was found.

Further allegations of a similar nature were received recently, said BP, and the company began an investigation, which is ongoing.

"Mr Looney has today informed the Company that he now accepts that he was not fully transparent in his previous disclosures," said the statement. "He did not provide details of all relationships and accepts he was obligated to make more complete disclosure."

Looney had served just under four years on the job.

This story is developing and will be updated.