Home secretary David Blunkett wants to change the law to allow hoaxers who cause anthrax scares in Britain to be sent to jail for up to seven years. Scotland Yard welcomed the decision to look again at the current laws.

Blunkett said: "Any evidence of hoaxes should be reported immediately to the police. These are malicious, criminal acts."

As Blunkett announced his plans, BBC staff were evacuated from the headquarters of the World Service in Bush House after an envelope containing a suspicious substance was found.