TERRORIST suspects are using encryption techniques to prevent police from accessing vital intelligence on seized computers, Britain’s top police commander said yesterday.

Sir Ian Blair, the Commissioner of the Metropolitan Police, said that government plans for counter-terrorist legislation should include prosecutions for suspects who refuse to unlock their computer files.

He said that the police can hold a suspect for 14 days without charge and if he or she refuses to co-operate the investigation becomes “a race against time” as police computer experts try to decrypt files in that time.

Encryption has become a “powerful tool” for the terrorists in recent years, he said.

The call for laws to combat the problem comes as security on the London Underground is tightened with the introduction of police sniffer dogs. British Transport Police confirmed yesterday that dogs are patrolling trains and stations in the biggest deployment that the force has mounted.

The dogs have already been used on the Heathrow Express and at Paddington. Now their deployment will be widened as a deterrent and to reassure the public. The dogs are taught not to tear at suspect packages or luggage. Instead they sit down by the object, indicating to their handler that they have found something.

The dogs will work at ticket barriers in groups, with back-up units of police, and search through trains. If anyone deliberately tries to avoid the dogs, usually spaniels or labradors, or leaves a station or train suddenly, they will be stopped by other officers.

Community support officers are also being drafted in to provide extra uniformed patrols on the Tube system.

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