Nottingham North MP Graham Allen said the government's Criminal Justice Bill to reduce the age of testing from 18 to 14 does not go far enough.

He said that by their teenage years, some of the children in his constituency were "old hands" at the drug scene.

The tests would take place on the children only after they have been arrested for other crimes.

Civil liberties

Mr Allen was speaking ahead of debate on the planned shake-up of the criminal justice system which has been put forward by Home Seceretary, David Blunkett's department.

He said: "The focus has been on the civil liberty aspects of the bill - my concern is the civic freedom of intimidated witnesses, innocent victims and frightened citizens.

Early intervention can deliver children and families from the misery of drug abuse Graham Allen, MP

"There are young people in my constituency who, by age 14, are "old hands" to drugs, and well known to local police.

"Drug testing of arrested children should begin at age 10.

"After all, 10 is the youngest age for criminal responsibility.

"If a child is taking drugs at age 10, then effective early intervention can save the taxpayers' money, reduce crime in the community and deliver children and families from the misery of drug abuse."

The bill has already sparked controversy for its plan to scrap the double jeopardy law and reveal defendants' previous convictions.

Mr Allen is a member of the committee of MPs which begins its scrutiny of the bill on Tuesday.