Police want a new body to be set up to investigate internet child pornography. It comes as new figures show arrests and convictions for downloading such images have quadrupled in two years. Home Office figures, revealed by children's charity NCH, showed 2,234 people were charged or cautioned in 2003, compared with 549 in 2001. The BBC has learned the proposed unit - dubbed the UK Internet Safety Centre - would be staffed by police, charity workers and computer experts. Many police admit that they are still only touching the tip of a very ugly iceberg It would operate around the clock to investigate reports of suspicious images found on the internet. "There would also be the capacity to carry out covert operations against internet paedophiles," BBC crime correspondent Neil Bennett said. The Inspector of Constabulary for England and Wales noted this week how much time the extra arrests were taking up for individual forces - sometimes to the detriment of other types of child protection. Stuart Hyde, from the Association of Chief Police Officers (Acpo), said law enforcement agencies, children's charities and internet service providers are united in calling for a national centre. NCH said the arrest figures showed the urgent need for a centre to be established. The charity's internet safety advisor John Carr said the "astonishing" figures reflected the arrests made during Operation Ore - a police operation hunting web paedophiles launched in 2002. "But given ongoing police activity, the worry is that they represent not a blip but a new 'normality'," he said. "Many police admit that they are still only touching the tip of a very ugly iceberg." Both police and NCH expressed concern over how the centre will be funded. Mr Hyde told Radio 4's Today programme: "We're not expecting the government to suddenly put massive amounts of money into this."