The UK government's new £25m internet surveillance centre has become fully operational, Computing can reveal.

The National Technical Assistance Centre (NTAC) acts as an intermediary between internet service providers (ISP) and law enforcement agencies for intercepting and reading emails and web traffic.

NTAC will act as a clearing house, taking requests for law enforcement agencies for interception of communications and liasing with the ISPs. It is likely to deal with several thousand requests a year, and is based at MI5 headquarters.

The centre has been decrypting seized computer data since summer 2001, but has now added the capability to intercept internet traffic and emails.

It was due to become operational last summer, but was delayed.

A Home Office spokesman confirmed the centre had gained 'operational capacity' in April, but refused to give further details.

But in a statement on its website, the Home Office notes: 'Use of encryption to protect stored computer files is increasing and threatens the prosecution of those with the greatest motivation to conceal the content of those files, such as pornographers and paedophiles.

'NTAC will undertake any processing necessary to make lawfully intercepted material intelligible. NTAC will not analyse the intelligible content of any intercepted material. That will remain a function for the agency which applied for the interception warrant.'

Roland Perry, director of public policy at the London Internet Exchange, said such a centre is needed because of the increasing complexity of communications used by criminals and the number of communications service providers.

'You need to be sophisticated and coordinated in the way you approach monitoring these people's communications,' he said.