Speaking in the Commons shortly after the Times first reported he had passed information to the Metropolitan Police, Sir Lindsay confirmed he had given the force “relevant” information, adding he considered it his “duty and responsibility”.
“It is regrettable this rapidly ended in the media,” he added.
He did not provide any details, but the BBC understands he passed on information he received in the British Virgin Islands during a visit last week that Lord Mandelson was planning to travel there.
The Met is understood to have conducted its own assessment of the credibility of the information passed on by Sir Lindsay before deciding to arrest Lord Mandelson on Monday afternoon.
The former Labour minister was taken to Wandsworth police station in London for interview, before later being released on bail pending further investigation. It is understood he surrendered his passport as one of his bail conditions.