Drug addiction is the "biggest crisis to face Britain", Iain Duncan Smith has warned as he unveiled Tory plans to offer treatment to every crack and heroin addict in the UK.
The Tory leader says drug-related crimes are on the rise
He said his party "has to win the battle against drugs and crime", because it is "hollowing society out from the inside".
Mr Duncan Smith said under a Tory government the numbers of residential rehabilitation places for hard drug addicts will be increased from under 2,000 to 20,000.
But Roger Howard, chief executive of the charity DrugScope, argued that the plans may prove prohibitively expensive.
He told BBC Radio 4's Today programme: "Any investment in residential
rehabilitation for drug treatment is expensive - increasing it to 20,000 is a
New York-style policing
The Tories have already said they would be willing to take almost half a billion pounds every year out of health spending to help young drug addicts beat their habits.
On Thursday, Mr Duncan Smith used the launch of the party's new crime strategy in Leeds to make a firm commitment on the numbers.
He said drug offences rose by 16% last year, with violent crime up by a fifth and gun crimes up by 35%.
After looking at crime fighting on the streets of New York and other places, a Tory administration would implement plans outlined last year to provide 40,000 more police officers, he said.
The Tory policy will focus on hard drugs first
"We want to give people a fair deal on the streets of Britain ... " he told the BBC.
"On the other hand, we have to cut the demand which fuels that violent crime through drugs and that is to give young people a way out - a tough choice - so rehabilitation, as we have seen in Sweden and many other countries, where they have reduced addiction, cut the levels of crime. We are going to copy that."
Mr Duncan Smith said his policy had been inspired by a visit to Gallowgate in Glasgow where he met many families whose children had died as a result of drug overdoses.
He said they had told him that nobody had offered these people "a way out", yet their streets were "amongst the most violent, the most crime ridden" places where "drive by gun crimes on a Friday night are a regular occurrence".
"There are so many families that I know of ... whose lives are blighted because one member of that family or more has got themselves involved in drugs," said Mr Duncan Smith.
"Everybody suffers as a result of this addiction, so what I am saying to people is: 'Look, this is the biggest crisis to face Britain."
His shadow home secretary Oliver Letwin has already unveiled plans to give young drug addicts a choice between getting treatment or facing court action.
Home Secretary David Blunkett said he welcomed the Tory "conversion" to his focus on Class A drug users.
But he argued: "This latest relaunch of the same Tory
drugs policy raises more questions than Mastermind...
"Plucking figures out of the air to make
attractive-sounding promises doesn't fool anyone."
Former government drugs czar Keith Hellawell welcomed support for treatment but said only the fine details of the policy would show whether it was more than "just spin".
Mr Hellawell told BBC News Online the efforts he had begun to have 100% of hard addicts in treatment by 2008 were on target to be met.
He questioned whether residential places were the best option.
"I found that people were isolated from their families and the community and having come back to the community they were extremely vulnerable.
"So we tended to favour community based treatment with parents and other people involved."
Drugs help charity Adfam praised the Tories for consulting the people best placed to give advice - families and groups working with drug users.
Chief executive Vivienne Evans said: "We welcome any pledge to underpin drug treatment programmes with consistent, guaranteed funding but only where the figures are realistic.
"The Conservatives must do more to substantiate the costs of the rehab they have used."
Danny Kushlick, director of drugs charity Transform, accused the Tories of "missing the point" as he argued enforcement of drugs laws had failed.
He told BBC News Online: "Treatment is not the issue. The major problem for drug misusers, be they young or old, is prohibition."