LONDON (AFP) - The British spy agency GCHQ will create a specialist unit to track child pornography and hunt abusers online, Prime Minister David Cameron said on Thursday.

It will be run by the Government Communications Headquarters (GCHQ), which has assisted investigations in the past but has never had a permanent unit, and the National Crime Agency (NCA).

"We are going to go after these people with every bit of effort that we go after terrorists and other international criminals," Cameron said at an anti-abuse conference in London.

GCHQ director Robert Hannigan said his agency would use its "world-leading capabilities to help the NCA reach into the dark web" and bring to justice "those who misuse it to harm children".

"We are committed to eliminating digital hiding places for child abusers," Hannigan said.

Cameron said British authorities had already taken down tens of thousands of abuse images and were planning to remove "millions" of files with the help of Internet giants like Google and Facebook.

The British leader also unveiled plans to tighten laws against child abuse via the Internet to make the act of soliciting nude images from children a crime of "sexual communication".

"If you ask a child to take their clothes off and send you a picture, you are as guilty as if you did that in person," he said.