The Assisted Voluntary Return Programme is designed to encourage failed asylum seekers who no longer have a right to stay in the UK to leave of their own accord. But it involves a cash bribe and other assistance to persuade them to leave.

In 2006, the package was worth the equivalent of £3,000 per applicant and 5,340 took advantage of the sweetener.

That represented about 30 per cent of the 18,280 failed applicants and dependents who were removed during the 12 months.

It means the taxpayer had to foot a bill for more than £16million to send home people who should not be here and could be forcibly removed.

The overall bill will be even higher because it does not include the cost of flying the people back home.

At the beginning of this year, then Home Secretary John Reid upped the bribe to the equivalent of £3,500 in cash and kind.

During the second quarter of 2007, almost 1,000 people left under the scheme: about 30 per cent of the 3,280 who were removed. The package has since dropped to £1,500.

Sir Andrew Green, chairman of Migrationwatch UK, said: “It is dangerous that our removals depend so heavily on cash grants.

“The result is that bogus asylum seekers are on to a no-lose option. If they pass the authorities, they get a meal ticket for life. If they fail, they get a free ticket home and a very handsome sum of money.”

A Home Office spokeswoman said: “Removals are always carried out at the lowest available rate and we promote voluntary returns as a cost-effective alternative to enforced removals. This is better for the taxpayer.

“The Voluntary Assisted Return and Reintegration Programme provides reintegration assistance of £1,500 per returnee that can be used to fund a small business start-up, vocational training or education.” A row is also brewing between local authorities and the Home Office over plans to allow thousands of so-called “legacy” asylum cases to stay.

Ministers are desperate to clear a backlog of 450,000 files and are set to fast-track approvals.

Town halls have been warned that 70 per cent of the first 7,000 cases are to get indefinite leave to remain by Christmas: seven times the current approval rate. Councils must house them.

If the rate is applied to the rest of the backlog, 315,000 asylum seekers and failed asylum seekers will be allowed to stay.