Microsoft announced the closure yesterday of all its internet chatrooms, to protect its customers, some of whom are teenagers, from paedophiles and unsolicited pornographic spam emails.

More than 10,000 chatrooms, for fans of such diverse hobbies and pastimes as beekeeping, Arsenal Football Club, Harry Potter and Motörhead, the heavy metal band, will be cut off on Oct 14.

Gillian Kent, director of MSN UK, Microsoft's online service, said it was "necessary to make these changes because on-line chat services are increasingly being misused for spam and inappropriate communication".

Although the move was welcomed by some child protection charities, several internet experts said Microsoft's motivation was more financial than a genuine concern about the types of conversation taking place in chatrooms.

Ian Angell, professor of information systems at the London School of Economics, said the measure was "rather draconian" and unlikely to make any immediate change to the risk of paedophiles "grooming" children online.

According to National Children's Home and Charities' Coalition for Internet Safety, at least 26 cases in Britain of children being raped or abducted by paedophiles had been linked to chatroom contact.

But Prof Angell said Microsoft's decision to close its chatrooms would simply result in children seeking other internet meeting rooms in which it may be even more difficult to trace paedophiles.