A top aide who advised British Prime Minister David Cameron on broadband internet filtering in the UK is being investigated over an allegation involving “child abuse imagery".

The man at the centre of the investigation was named last night as 62-year-old Patrick Rock, a powerful advisor to the Conservative Party for 30 years. It's understood Rock, who was deputy head of Number 10's policy unit and tipped for a peerage, was instrumental in Cameron's push for website blockades in the UK.

Rock resigned after he was arrested and quizzed by police. Cops then searched computers and other IT equipment at Number 10. A Downing Street spokesperson issued the following statement today:

On the evening of February 12th Downing Street was first made aware of a potential offence relating to child abuse imagery. It was immediately referred to the National Crime Agency (CEOP). The Prime Minister was immediately informed and kept updated throughout. Patrick Rock was arrested at his home in the early hours of February 13th, a few hours after Downing Street had reported the matter. Subsequently, we arranged for officers to come into Number 10 have access to all IT systems and offices they considered relevant. This is an on-going investigation so it would not be appropriate to comment further, but the Prime Minister believes that child abuse imagery is abhorrent and that anyone involved with it should be properly dealt with under the law.

The National Crime Agency's website and social network feeds are silent on the matter, as are the Prime Minister's.

We'll update as the story develops. ®