Some of Britain's biggest high street lenders have refused to join a long-awaited government plan to support homeowners at risk of repossession.

Not one UK bank that is not owned or controlled by the State has pledged to join the Homeowners Mortgage Support scheme, launched yesterday.

Lenders that have refused to take part - representing more than half the mortgage market - include Abbey, the UK's second-biggest lender, Nationwide, Barclays and HSBC. The Government's failure to get them to sign up leaves more than five million homeowners outside the scheme.

Peter Vicary-Smith, chief executive of Which?, the consumer association, said: “It's disappointing that some lenders have decided not to sign up. This scheme is a great step forward and offers much-needed protection for people who find themselves in financial difficulty.”

It is estimated that 28,000 borrowers have been repossessed in the time it has taken the Government to finalise the details of its plans.

Under the terms of the scheme, borrowers suffering a sudden drop in income will be able to defer 70 per cent of their monthly mortgage interest payments for up to two years. Only owner-occupiers with mortgages under £400,000 and with less than £16,000 in savings can apply.

Critics point out that the deferred interest is rolled into the total mortgage debt, putting up monthly payments for homeowners in the long term.

Ray Boulger, of John Charcol, the mortgage broker, said: “This scheme may be useful for a small number of homeowners, but for other borrowers it could make the situation worse.”

The state-backed Lloyds Banking Group, Royal Bank of Scotland, Northern Rock and Bradford & Bingley are participating. Clydesdale and Yorkshire banks, owned by National Australia Bank Group, have also pledged support. The only building society to sign up is the Cumberland.

The Post Office, Standard Life Bank and the sub-prime lenders GE Money, GMAC and Kensington Mortgages are still in talks with the Government.

A spokesman for Abbey said:“Abbey offers similar levels of forbearance to those offered under the Homeowners Mortgage Support scheme. On this basis our participation would be extremely limited and therefore we will continue with our own programme, which we believe meets the Government's objectives.”

Industry insiders suggest that banks have been put off by the administration required to set up the scheme. There was also concern that borrowers could try to sue banks that advised joining the scheme if, after two years, the net result was that an individual was still repossessed, but with a bigger rolled-up debt than previously.

The Council of Mortgage Lenders insisted that those of its 135 members not in the scheme would still offer help to homeowners in arrears.