Britain's most senior police officer backs new data powers

Metropolitan Police Commissioner Sir Bernard Hogan-Howe said the introduction of the legislation - labelled a "snoopers' charter" by critics - had been "delayed too long" during the previous parliament.

He warned that unless police are given powers to "plug the gap" in intelligence-gathering then only the terrorists can "win".

The Bill, which would increase the amount of data gathered about people's activity on the internet, was shelved in 2013 after opposition from the Liberal Democrats.

It is thought Home Secretary Theresa May will return the proposals to the agenda following the Tories' election victory.

Sir Bernard said of the expectation that the measures would be pursued: "It is a welcome development, and a vital one, which had been delayed too long under the coalition government."

He said digital evidence is often fundamental to investigations, adding: "Therefore we need help, because in some areas it's going dark. If we cannot get this data for whatever reason we are going to struggle to investigate and prosecute.

"Unless we plug that gap, the only people who can win are the terrorists."

Police said monitoring threats is more difficult in the wake of the Snowden revelations about surveillance operations by intelligence agencies.

Assistant Commissioner Mark Rowley said: "We are dealing with this in a world where intelligence coverage is increasingly hard to achieve, particularly in the post-Snowden environment, and we are dealing with more and more ambiguity.

"That ambiguity is created firstly by so much taking place on social media and you can't observe it all, but you've also got people trying to propagate attacks by using social media, trying to recruit people across countries.

"Our ability to penetrate that post-Snowden is less good than it was, our visibility is less good than it was, which I think is why the Government is wrestling with potentially more legislation to try and repair powers that we are losing."