Thousands of immigrants are prepared to die in their bid to come to the UK, MPs have been warned.

The mayor of Calais, Natacha Bouchart, said there were currently 2,500 migrants in the French channel town desperate enough to risk their lives to undertake the journey.

Her warning came as it emerged the Coalition Government will not support future search and rescue missions in the Mediterranean to save desperate immigrants from drowning when they seek to make landfall in southern European countries en route to the UK.

Labour criticised Tory-Lib Dem ministers after one suggested the rescue service encouraged migrants to take the risks in making the perilous journey.

Meanwhile, a damning new report by MPs found that 11,000 asylum seekers in the UK have been left waiting at least seven years to be told if they can stay in the country.

Officials have lost track of a further 50,000 illegal immigrants.

MPs attacked a "mess" of a system, which they said had also left taxpayers with a "gobsmackingly awful" IT bill for £1billion.

In another blow to David Cameron, one of his key allies also warned the UK may never be able to control EU migration.

Nick Boles, the skills minister, said there would be a "large" influx of immigrants for as long as the UK economy outperforms the continent.

The Prime Minister is looking at ways to restrict European immigration as he fights another tough Westminster by-election against Nigel Farage's Ukip in Rochester, Kent.

Mr Boles said: "We may never be able to control it (migration) entirely, because it's a fundamental principle of the EU, but it will be very hard for the British people to accept, that, for as long as Britain remains the most dynamic economy in the EU we're going to be the net recipient of a very large amount of immigration every year."

The report by the Public Accounts Committee (PAC) also found that the Home Office has still not resolved some 29,000 asylum applications which date back to at least 2007.

Ministers scrapped the UK Border Agency (UKBA) in March last year in part amid concerns over a backlog of cases.

But the report found that of the 29,000 cases still unresolved, a "worrying" 11,000 had not had an initial decision reached on how to proceed with them.

The department is also missing new targets to process asylum claims while the cancellation of two major IT projects, intended to ease the pressure on this issue, has also seen close to £1bn wasted, the committee said.

The report accused Mr Cameron of "presiding over one failure after another in our immigration system."