Leading internet companies have been summoned to a meeting at Westminster in Britain in an attempt to crack down on child abuse online.

Firms including Google, Microsoft and Facebook will attend a summit called by Culture Secretary Maria Miller. They will be expected to come up with ways to stop access to child abuse images and report back with an action plan.

The meeting comes after two child killers were found to have viewed child pornography online.

Mark Bridger, convicted of murdering 5-year-old April Jones, and Stuart Hazell, who murdered Tia Sharp, 12, both accessed abusive images.

In the 12 days since the summit was announced, web giants have already taken some action. British firms TalkTalk and BT have announced that customers trying to view inappropriate material will be confronted by a pop-up warning.

And Google has pledged millions of pounds to organisations who try and tackle child abuse online, such as the Internet Watch Foundation who maintain a blacklist of images.

UK Culture Secretary Miller said "Child abuse images are horrific and widespread public concern has made it clear that the industry must take action. Enough is enough. In recent days we have seen these companies rush to do more because of the pressure of an impending summit. Imagine how much more can be done if they seriously turn their minds to tackling the issue. Pressure will be unrelenting."

It is unclear exactly what concrete action - if any - the British government will demand from the meeting.

Companies providing internet services in Britain have already rejected a call from the adviser to the UK Prime Minister to impose parental filters for adult content as a default setting when viewing content online.

The Internet Service Providers Association said it remained opposed to default filtering because it "can be circumvented and lead to over- or under-blocking" of offensive web pages.