Violent crime is rising in Barnet while its police officers are spending more time than ever in central London, according to Ken Livingstone's main challengers for Mayor of London.

As election day looms next Thursday (June 10), both Liberal Democrat Simon Hughes and Tory Steven Norris went on the offensive about Mr Livingstone's record on crime.

Barnet's officers spent more than 4,000 days away from the borough last year up 38 per cent from the previous year, said Mr Hughes.

Violent crime has increased in Barnet by almost ten per cent in the year to April, more than double the London average, according to the most recent Metropolitan Police statistics, added Mr Norris.

Both men defied a pre-election plea by Sir John Stevens, the Metropolitan Police Commissioner, not to make crime a party political issue.

In fact Mr Norris wants to sack Sir John and replace him with someone who will not accept the status quo', according to a spokesman.

He is reported to be considering the Met's deputy commissioner Ian Blair and Hugh Orde, chief of police in Northern Ireland, for the job. Current legislation rules out trying to replicate the success of New York by appointing an American for the job.

Mr Hughes said that, in the year to February, each of Barnet's 539 police officers spent an average of eight days on duty in central London.

Many were called in as a result of the capital's high state of terror alert.

Mr Hughes said: "When local police are removed from their front-line duties, crime in those boroughs increases. Despite numerous promises from Mr Livingstone, more police are being removed from their duties than ever before."

Mr Norris said he too would stand up for the suburbs. "When I am Mayor, I will insist that we put hundreds more police officers on the beat in places like Barnet," he said.

Chief Superintendent Sean Walters, of Barnet police, denied Barnet was losing out unfairly. "It is my continued aim to target officers to local issues but I must accept my London-wide responsibility," he said.

Mr Livingstone said he was already delivering extra police for Barnet. He said Barnet police had increased in size from 485 officers when he was elected in 2000 to 539 today.