I think it is a very good way to indicate our support for marriage

William Hague

The Tories say the policy will help those in most need but Labour has dismissed the plan as "a con", saying the figures do not add up.

Under the plans, a parent who chooses to stay at home to look after a child would be able to transfer tax allowances to the working partner.

The measure, which would be limited to basic rate tax relief, would be introduced in 2003 at a cost of �1bn a year.

Help couples

Mr Hague said the measure would help couples with children when they most need financial assistance.

"Obviously it doesn't help everyone but it helps those who need it at the time," he said.

"I think it is a very good way to indicate our support for marriage."

Mr Hague has long pledged to bring back a version of the married couple's allowance.

But criticis have accused him of backtracking on previous promises to restore the married couples allowance in full.

The last Tory government began phasing out the allowance and it was abolished by Chancellor Gordon Brown in 1999.

'Clobbered under Labour'

Mr Hague's promise follows Tory pledges of tax breaks to help savers, pensioners, families with young children, and Michael Portillo's announcement on Tuesday that widowed parents will also benefit.

Speaking to BBC News, Mr Hague said: "These are all people who have been clobbered under the Labour Party and they need help."

Michael Portillo: "Help for widowed parents"

He added: "We are now setting out our policies for the election.

"They are very clear and these will be the polices that will be in our election manifesto."

He rejected criticism that the Tory sums did not add up.

"Our tax proposals have to be clearly costed and we have to be able to pay for them," he said.

"They clearly can be delivered."

Irresponsible

But Labour has suggested that this latest tax break will only benefit one in five families.

Andrew Smith, Chief Secretary to the Treasury, said: "Of the 10 million married couples who are taxpayers over eight million will not benefit because they do not fall into the categories chosen by the Tories."

He added: "These Conservative proposals are a con. They don't add up and are another irresponsible promise that they cannot deliver on."

On Tuesday, shadow chancellor Michael Portillo said a Tory government would scrap tax on both the widowed parent's allowance and any stake their partner had in the government-operated Serps pension scheme.

About 50,000 families would benefit, he said.

Those earning �15,000 a year and receiving �15 a week from the State Earnings Related Pension Scheme would be more than �1,000 better off.

Supporting people

Mr Portillo said the proposal was a "significant" boost for widowed parents and part of the Tories' commitment to helping families with children.

Mr Portillo said: "Our approach is to help people, often at their time of greatest need, by leaving them more of their own money to support themselves and their families.

"We believe in supporting people who have responsibilities and who take on responsibilities."

The Conservatives have now used up about �5.5bn of the �8bn savings they say they have identified to fund tax cuts announced in the run-up to the general election.

Liberal Democrats spokesman Matthew Taylor criticised the Tory plans.

"The Tories are raining false expectations amongst millions of needy families that their taxes will be cut.

But William Hague's Conservatives have in fact failed to explain how they could find the money without cutting funds for schools, hospitals and pensions."