The NSPCC has welcomed Google and Microsoft's decision to block images of child abuse via their search engines, but emphasised, "We must keep one step ahead."
Peter Wanless, chief executive of the children's charity, said:
Each image is a crime scene where unspeakable abuse was committed.
As sex offenders get ever more technologically advanced in pushing their vile trade, we must keep one step ahead and this requires a concerted and sustained effort from all quarters.
This is the key child protection issue of a generation - we cannot fail.
These are dramatic new steps which will make the internet safer and better for children, a leading Internet safety expert writes.
The search engines have stepped up to the plate - their reforms will help remove video child abuse content more quickly and comprehensively.
Former chief of CEOP Jim Gamble said the government must ask whether they are doing enough in the internet safety debate.