This was highlighted recently when the 33-year-old sex offender Peter Chapman used Facebook to make contact with a teenager whom he raped and killed. He used a fake profile and photographs on Facebook to pretend to be a teenager himself.
On Tuesday, the Child Exploitation and Online Protection Centre (CEOP) which tackles child abuse in the UK, said Facebook has not installed the CEOP's "alert button" using which youngsters could report suspicions about online paedophiles or cyber-bullies.
Currently, networking sites such as Bebo and MSN Messenger use CEOP's tool.
Of the 267 reports that the CEOP received about suspicious activity on Facebook last year, only one or two reportedly came from Facebook, it said.
Facebook says its system is good enough to handle suspicious reports and that its staff co-ordinates with the police when it receives such reports.