A firm in the north-east of England has spent three years developing a scanner that will make it harder for paedophiles to prey on youngsters via the internet.

Think2gether, which is based in Gateshead, says the scanner is the first secure access system for chat-room users.

For about pound;30 schools will be able to buy the thumb-print scanner, which is already being used at the South Tyneside city learning centre and in Leicester education action zone.

Alan Wareham, director of Think2gether, said the system had attracted interest from as far away as Singapore.

“The problem is that children often tell other people their password, which is something adults tend not to do,” he said.

“A child can pass on this information in all innocence and the adult can then log on as that child and pretend it is them using the chat-rooms.

“The scanner removes this possibility by scanning the child’s thumb-print three times before letting them in. We are also developing hardware which will monitor and record conversations in chat-rooms, as additional protection.”

Last week, Microsoft announced it was to close its British internet chat-rooms on its MSN site. The move was welcomed by children’s charities that said it would close a route through which paedophiles could gain access to children.

Rival service providers accused the firm of driving the problem underground, and urged the greater use of moderators to police the network.

But Mr Wareham said: “Moderators may not see what is being written until some time after it has appeared, and by then it might be too late. Our idea allows children to communicate effectively and in a safe environment.”

The thumb scanner can also double as a registration system.

“Every time a child logs on using their thumb-print, it can record where they are in the school,” Mr Wareham said.