Plans to provide safer blood clotting treatments for more than 4,000 patients with haemophilia within three years are threatened because of a shortage of funds.

The 1,500 people in most need of the clotting factors will get them first but some, including those who might need treatment only after accidents or operations, may have to wait until after March 2006, after the public spending review.

The programme, announced in February, is designed to minimise the risk of infection through contaminated blood products and end an anomaly under which most patients over 16 in England do not get the safer synthetic alternative known as recombinant.

In Scotland and Wales all patients have the product, while in England only children with haemophilia do, although for them, the treatment has continued into adulthood.

Ministers announced the extension of recombinant's use in the hope of ending a dispute over equality of treatment. But it has emerged that the funding, £88m to April 2006, might not be enough, because of rising prices and increased use of recombinant.

Paul Giangrande, head of the Oxford haemophilia centre, said: "We are delighted the money has been made available but we don't think it is going to be enough, and you can't predict whether Joe Bloggs in south Milton Keynes is going to fall off his bike and need treatment."