Police are shutting websites without keeping any records, hampering government efforts to address online extremism, it's been revealed.

The Terrorism Act 2006 granted powers for police to compel web hosts to shut down websites promoting terrorism. But the powers have never been used, and forces have instead persuaded providers to take down websites voluntarily, according to the security minister Lord West.

He told the Lords on Wednesday that he could not say how many websites have been censored because no records have been kept.

"When we passed the Act in 2006, we laid down a requirement to make such records, but it has not really been done," he said.

"The Office for Security and Counter-Terrorism is now talking in great detail to the Association of Chief Police Officers, and the requirement will be met. We need to make sure that records are properly kept because we need to have precise facts to work on."

When measures against extremist websites were announced, the government suggested ISPs might introduce filtering arrangements similar to the Internet Watch Foundation's blocklist of URLs leading to images of child abuse. No system has emerged, however, and industry sources say the idea is not being discussed.

SOCA and GCHQ are both involved in investigating extremism online, and regional police act to shut websites down where possible. However, in common with abuse sites, most extremist sites are hosted overseas.

"A lot of this is abroad — it is carried on by ISPs abroad," West said.

"We have to deal with them internationally. However, I can assure this House that we are really working hard in this area. We will jolly well get there, and we will jolly well knock them for six finally.

"Finding out who has done something, finding out which server the information is on and where it has come from, is very difficult. It takes very detailed and hard work. I am glad to say that we have some of the best people in the world doing this work, but it is highly complicated." ®