The reform will come in a family justice bill which will also open the family courts to the press, subject to strict rules about anonymity.

Harriet Harman, the family justice minister, told the Guardian yesterday that although the legislation would not be in the forthcoming Queen's Speech, it would be brought forward "soon". It is thought it could be introduced as early as next year.

Under the plans, people who live together outside marriage should be able to claim lump sums, a share of property including the family home, regular maintenance payments or a share of their partner's pension when they split up.

The claims would not be automatic; individuals would have to prove either that they had suffered a significant financial disadvantage from the relationship or that their partner had gained a significant financial advantage.

The government is thought not to favour barring the childless from applying or restricting rights to a fixed term of living together, although it recognises that people with children and long-term cohabitees would be more likely to qualify.

"There is evidently a problem where a couple have lived together a long time, brought up children together, she's stayed at home so he could go out to work and pay the mortgage, and she discovers at the end of the relationship that she's left without a roof over her head," Ms Harman said.

With two million couples now cohabiting outside marriage, many with children, there is growing pressure to provide redress for vulnerable partners. Scotland brought in a law last May to allow cohabitees to make limited claims against each other. Research shows that few people are aware of their lack of rights and many wrongly believe that cohabitation makes them "common law" spouses with rights similar to those of married couples.

Many contribute to the deposit or mortgage payments on a home in their partner's name, or reduce their earning capacity by looking after children, only to receive little or nothing when the relationship ends.

The move towards new rights for cohabitees is in line with preliminary recommendations from the law commission, but ministers have decided in principle to go ahead even though the commission's final proposals are not expected until next summer.

Under the proposals for England and Wales, claimants would not have the automatic rights divorcees have. The commission recommended provisionally that people with children should be allowed to make claims, and asked for views on whether the rights should also extend to those without children or be triggered by a certain period of cohabitation - say two years - as happens in some other countries.

The law commission also recommended that couples should be able to opt out of the law by signing a legally enforceable cohabitation contract stating what would happen if they split up.

The Church of England said it was "sympathetic to reform that addresses the effect of relationship breakdown on children and those who make sacrifices to care for them". But it rejected new rights for childless cohabitees based on length of cohabitation.

The bill incorporating the reforms would open hearings in the family courts to accredited journalists in an effort to counter allegations of "secret justice" and restore confidence in the family justice system. Hearings are currently held behind closed doors.

"It is of great concern that there is a lack of confidence in the family courts," Ms Harman told a conference in central London yesterday, held to mark the end of a public consultation by the Department for Constitutional Affairs on opening the courts.

"Fathers complain of bias against them and failure to enforce contact orders. Mothers complain that the court orders them to give contact to dangerous fathers who threaten violence against both the mother and the child. And the courts are accused of taking children away from loving families and placing them for adoption. And at the same time the courts are accused of leaving children too long with parents who are a danger to them.