That follows a threat from Prime Minister David Cameron who said that the companies must come up with the technology or he will implement legislation to force them to do it.
But the former head of the Child Exploitation and Online Protection Centre said that it was unlikely the measures would make much of a difference.
Jim Gamble told the BBC said that the major search engines have already been blocking such content. He said a better step would be for the government to put more funding in police regions to employ experts to hunt down paedophiles.
He said that the dark corners of the web were where offenders lurked, often using peer to peer networks.