Ashford MP Damian Green has been asked by the Metropolitan Police to hand over emails exchanged with former Shadow Home Secretary David Davis, it has emerged.

Police have asked for the emails as part of their investigation into the MP’s role in the alleged leaks of Home Office documents.

Details of the police request were disclosed in the House of Commons by Mr Davis, who told MPs about the matter and asked the Speaker of the Commons whether a warrant should have been sought.

"My honourable friend [Green] has been approached by the Metropolitan Police and asked for access to emails between him and myself as frontbenchers of Her Majesty’s loyal opposition. Does this come under your [Martin’s] ruling that it will require a warrant and will be referred to you for your personal decision?"

The Speaker replied: "This is news to me and I will investigate as to [whether] the proper protocol and also the procedures I laid down for situations without a warrant have been gone through."

Meanwhile, Boris Johnson has said he warned police about the impact of arresting shadow immigration minister Damien Green.

The Mayor of London has been giving evidence to a Commons committee which is examining how police handled the arrest of the senior Tory Ashford MP in connection with the leak of Home Office documents.

Mr Johnson says he rang the deputy head of the Metropolitan Police warning him that their actions would "go off like a rocket".