Some farmers could have to repay thousands

The Rural Payments Agency, already under fire for delays in payouts, said it would review one-fifth of them amid fears they may have been wrong.

While many farmers could get top-ups, others are facing paying money back.

The agency is responsible for allocating about �1.5bn under the EU's single farm payment scheme.

Martin Haworth, director of policy for the National Farmers' Union (NFU), said: "We know terrible mistakes have been made and that a lot of the payments will have to be reviewed.

"In many cases that is because a farmer has not received what was expected and has raised a query.

"Sadly this means the Rural Payments Agency is still unravelling last year's mess when it should be concentrating on getting this year's system right.

"There is therefore a very high risk of yet more delay and confusion - which is why the NFU is pressing Defra to announce a substantial part payment of the 2006 entitlements in December."

The Rural Payments Agency said the payment review was a housekeeping exercise and the priority was always to get the money out as quickly as possible.

Consistent problems

Since its introduction last year, the payment scheme has been dogged by problems.

The government promised the bulk of the money would be paid by February, but most farmers were left waiting until the end of June.

There were computer problems and in April the government agreed to make partial payments to help farmers facing financial problems.

At the end of August, the agency announced it had paid out almost 98% of the fund to a total of 111,829 claimants.