British police are working with Australian and US counterparts to break a Philippines pedophile ring that has been streaming live scenes of child abuse over the internet, the National Crime Agency says.

The NCA, which has been investigating the ring since it discovered obscene videos on a British pedophile's computer two years ago, called abuse in developing countries "a significant and emerging threat".

"This investigation has identified some extremely dangerous child sexual offenders who believed paying for children to be abused to order was something they could get away with," said the agency's Andy Baker.

"Being thousands of miles away makes no difference to their guilt.

"Protecting the victims of abuse is our priority and that means attacking every link in the chain, from dismantling the organised groups who are motivated by profit through to targeting their customers," he added.

The inquiry - called Operation Endeavour - has taken place in 12 countries and led to the arrest of 17 Britons, five of whom have been convicted. Fifteen children aged between six and 15 have been rescued.

Three other investigations into live streaming of child abuse have netted 733 suspects globally.

The investigation was sparked when Northamptonshire Police seized the computer of registered sex offender Timothy Ford, who was later jailed for eight-and-a-half years after being found guilty of paying to view live sex abuse.

The NCA added: "The use of webcams to stream live abuse, particularly from the developing world, is a significant and emerging threat according to the NCA's CEOP (Child Exploitation and Online Protection) command.

"Extreme poverty, the increasing availability of high-speed internet and the existence of a vast and comparatively wealthy overseas customer base has led to organised crime groups exploiting children for financial gain," it warned.