Eavesdropping criminals who use scanners to monitor North Yorkshire police will be foiled by the force's new digital radio system.

Villains are currently able to keep tabs on police movements using equipment available from high street shops for just £70.

But the new system, to be introduced next year, will allow officers to keep one step ahead of the lawbreakers.

Chief Constable David Kenworthy told a crime and disorder conference at York's Mansion House yesterday that the scanning of police frequencies was a problem when it came to fighting crime.

"They can pick up anything we say on radios, but that will change with our new radio system," he said.

Mr Kenworthy said that as criminals became more sophisticated, the force had to counter them.

"Villains have more resources available to them than we do, and it is a constant battle," he admitted.

York's police chief, Superintendent Gary Barnett, told the conference that the proliferation of mobile phones was putting an increasing strain on the force's communications.

He said that whereas previously the control room would receive one call from the public following a road accident, they could now expect to get between 50 and 100.

"All of these have to be answered with the necessary level of customer care, but it is an enormous demand on our communications," said Supt Barnett.

He said the strain put on the police by the sheer number of mobile phones in circulation was illustrated by the recent petrol crisis.

"We had an enormous number of calls from people asking where they could buy petrol.