The Conservatives are set to outline new polices on rehabilitation treatment for drug users.

Party leader Iain Duncan Smith and shadow home secretary Oliver Letwin are set to pledge that a future Tory government would boost the number of rehabilitation places from under 2000 to more than 20,000.

The move has echoes of Labour's successful "tough on crime, tough on the causes of crime" campaign slogan.

As proof of the need for the new policy, Duncan Smith will tell an audience in Leeds that drug offences rose by 16 per cent last year.

"These figures are shocking enough. But behind them are real stories of fear, pain and tragedy," he will add.

"Crime is infecting our nation - and hard drugs are making our condition worse."

He will also call for a greater emphasis on tackling drugs and crime, challenging Labour's record since it took power in 1997.

"The point about these two policies is that it's no longer good enough simply to contain the problems of crime and drugs. We have to defeat them," the Conservative leader is expected to say.