HUNDREDS of thousands of young people could be stripped of housing benefit and forced to live with their parents as David Cameron signals an end to what he calls Britain's "welfare gap".

The Prime Minister will say in a keynote speech today it is "time to go back to first principles" about who gets what state benefit as he claims a large swatch of people are entrenched in a dependency culture.

Mr Cameron will also raise the prospect of stopping feckless claimants' dole money if they refuse to find work and forcing workshy ones to undertake community work or face losing all of their benefits. He will also tread on the politically difficult ground of talking about restricting entitlement to child benefit to, say, three children.

Mr Cameron will say: "We have been encouraging working-age people to have children and not work, when we should be enabling working-age people to work and have children. At a time when so many people are struggling, isn't it right that we ask whether those in the welfare system are faced with the same kinds of decisions that working people have to wrestle with when they have a child?"

Labour denounced Mr Cameron's plan as "hazy and half-baked" and suggested if the PM really wanted to tackle the dependence culture, he should have a growth agenda for jobs.

"If the Government are really serious about dealing with the benefits bill, they've got to get the economy moving again, they've got to get people back to work," said Rachel Reeves, shadow chief secretary to the Treasury.

However, much of what Mr Cameron is suggesting is not likely to become policy this Parliament as the Liberal Democrats are unlikely to agree on many of the suggestions. Danny Alexander, the LibDem chief secretary to the Treasury, said he was "relaxed" about the remarks, saying they were being made by Mr Cameron more as Conservative leader than as Prime Minister.

Another Liberal Democrat source suggested that, in the light of the flak Mr Cameron had recently received from the Tory right, he should be allowed some leeway to float Conservative policies that might be in their next manifesto.

In Kent, Mr Cameron will describe the "welfare gap" as one between those living long-term in the welfare system and those outside it. He will say: "The system is saying to these people: 'Can't afford to have another child? Tough, save up. Can't afford a home of your own? Tough, live with your parents. Don't like the hours you're working? Tough, that's just life'. So there is a welfare gap that exists in our country. It is real and it is divisive."

He will argue compassion is "not measured out in benefit cheques" but in the "chances you give people – the chance to get a job, to get on".

Controversially, the PM insists Britain will have to rethink who receives welfare and will raise the case of under-25s on housing benefit, for which the taxpayer pays £2 billion a year. He will say: "There are currently 210,000 people aged 16-24 who are social housing tenants. Some will genuinely have nowhere else to live – but many will."

He will contrast how for almost three million people between 20 and 34, the "passage to independence is several years living in their childhood bedroom as they save up to move out, while for many others, it's a trip to the council where they can get housing benefit at 18 or 19 – even if they're not actively seeking work".

He will add: "The point is this: the system we inherited encourages them to grab that independence, rather than earn it. So we have to ask: up to what age should we expect people to be living at home?"