Rishi Sunak may have handed over even more cash to Rwanda as he desperately tries to resurrect the flagship deportation plan, MPs heard.

The Government is already known to have given £140million to the African nation, even though no asylum seekers have yet been sent. But a top civil servant has hinted the real figure could be even higher.

Officials were also forced to admit they have no idea where more than 17,000 asylum seekers who withdrew their applications last year had gone. It sparked allegations that ministers have been "cooking the asylum books".

Mr Sunak is under pressure to abandon the controversial Rwanda project, which was torpedoed by Supreme Court judges a fortnight ago. Despite the landmark decision that it is not a safe country to send asylum seekers to, ministers are working out ways to change the law as Tories descend into civil war.

A top Home Office official didn't deny that more cash could have been given to the Rwandan government, but told MPs they'd have to wait months to find out. Sir Matthew Rycroft told the cross-party Home Affairs Select Committee: "So there are additional payments each year and ministers have decided that the way to keep you and other colleagues in Parliament updated is once a year to set out the total additional payments to the government of Rwanda.

"And we'll do that in the annual report and accounts." The UK handed over an initial £120million when the deportation deal was agreed last year, and a further £20million covering 2023/24. But pressed on whether further sums have been paid, Sir Matthew said:"We will announce that in the normal way next summer."

Dame Diana Johnson, who chairs the committee, said it is hard to scrutinise the policy when the figures are being withheld. And Shadow Immigration Minister Stephen Kinnock said handing over more money is an "affront to the hard-working British taxpayer".

Even Tory deputy chairman Lee Anderson vented his fury, telling the committee: "I find this absolutely staggering that the big boss hasn't got a clue, not just on this question, but nearly every other question we've asked today."

Mr Sunak has previously said he expects a new treaty with Rwanda to address some of the concerns raised by Supreme Court judges. And ministers are working on emergency legislation they say will prevent legal challenges.

Sir Matthew said the Home Office is putting "finishing touches" to the new treaty. But the PM was hit by a further headache when former Tory children's minister Tim Loughton questioned a 300% rise in asylum seekers withdrawing their applications last year.

Asked if he knew where 17,316 people who did so are, Simon Ridley, interim second permanent secretary at the Home Office, responded: “I don’t think we know where those people are, no.”

Labour's Mr Kinnock said: "Home Office officials let the cat out of the bag that under the Tories, 17,000 asylum seekers have gone missing. Labour first warned back in August that the Conservatives were cooking the asylum books by withdrawing claims for asylum seekers for spurious reasons, and then allowing those individuals to drift away undetected into the underground economy."

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