The plan is aimed at boosting parenting skills and a 'fresh start in life'
A senior Labour MP has raised concerns about plans to house teenage mothers in supervised hostels, saying the policy may be counter-productive.
Barry Sheerman said "big institutions" were not the place to give vulnerable young parents the support the needed.
A key announcement in Gordon Brown's conference speech, he said the scheme would make young mothers more responsible and benefit wider society.
The Conservatives say the policy is not new and too few people would be helped.
'Network of homes'
Under the proposal, all 16- and 17-year old mothers on benefits who cannot depend on family support will be given places in a "network of supervised homes" rather than council flats.
This would help them to improve their parenting skills, gain responsibility and have a "fresh start in life", Mr Brown said.
But Mr Sheerman, chairman of the schools and families select committee, said he was not sure this was the right approach.
While he said he opposed teenage mothers being left to fend for themselves in council flats, he told the BBC any move towards collective hostels needed to be treated with care.
"I thought the language was a bit concerning because this is an area where we know big institutions don't work.
"You need these things to be quite intimate, to recreate a family atmosphere.
"Hostels don't work. They are magnets for pimps and people who prey on young women. You have to be extremely careful. They are very vulnerable young people and they need support."
Mr Sheerman, a persistent critic of Gordon Brown's leadership in recent times, said the idea was "very reminiscent of policies that have been flirted with and not delivered on" in the past.
The Conservatives have claimed that the policy was first put forward in 1999 and again in 2003 but on neither occasion was it followed up. They also claim that funds are currently only available for 500 places.
Ministers have been urged to make clear whether young mothers would be forced to agree and how many might be affected.
In an interview on Wednesday, Mr Brown said two-thirds of teenage mothers on benefits currently live in council-provided accommodation and this must change.
"I don't think that is right. They are living in a way which does not change their lives."
He added: "Hostel accommodation seems to work. It not only gives the mothers support with their children, they give them help to get a job."
The Foyer Federation, which accredits existing hostels for young parents, said the system did work as it offered specific support and required people to abide by set rules and services.
"My understanding is this is about building on good work done by lots of organisations that provide holistic support for young people and young parents," said its chief executive Jane Slowey.
"If you are starting out in life as a young parent, you need more than the keys to an isolated flat and a job with no prospects. You need quite a lot of intensive support."