Labour’s plan to scrap the Rwanda asylum scheme would “throw open the front door” to mass immigration, a minister has warned.

Michael Tomlinson said Sir Keir Starmer’s intention to process applications overseas would make Britain a magnet to illegal migrants.

The Labour leader has previously dismissed the bid to deport some asylum seekers to the African nation as a “gimmick” and made clear his party’s opposition.

Shadow home secretary Yvette Cooper and shadow immigration minister Stephen Kinnock have reportedly been speaking to asylum experts to draw up an alternative proposal to tackle small boats crossings in the Channel.

Former home secretary Lord David Blunkett and other European countries have also been consulted over a plan that would see successful asylum applicants allowed to come to the UK.

While explicit backing for an offshoring scheme would mark a significant shift for Labour, Sir Keir did signal earlier this month that he would not be opposed to considering such an approach.

“Other countries around the world do have schemes where they divert people on the way and process them elsewhere. That’s a different kind of scheme.

“And, look, I’ll look at any scheme that might work,” he told reporters after a speech in Buckinghamshire.

Labour has reportedly drawn up “three tests” for any such scheme – that it is cost-effective, credible enough to deter migrants, and would avoid the legal challenges that have delayed the Rwanda plan.

Senior party sources said that in theory they could back an offshore asylum processing scheme in Rwanda but it would be unlikely to meet the value for money or credibility test. “The cost and practicality would rule it out,” a senior party source said.

They added that specific destinations had not yet been drawn up and the party would need to wait until it was in government to negotiate with other countries.

The party is also considering allowing migrants to apply for asylum before arriving in the UK under a policy described as “upstreaming”.

Senior party sources pointed to the example of the Ukraine refugee scheme that allowed families fleeing the war with Russia to apply from other countries such as Poland on their way to the UK.

One party insider gave the example of allowing refugees fleeing violence in the Middle East to claim asylum from a British embassy in Turkey.

Prime Minister Rishi Sunak and Home Secretary James Cleverly are hoping fresh legislation, currently in the Commons, will be enough to revive the flagship policy after it was declared unlawful by the Supreme Court earlier this year.

According to The Times a Labour “red line” would be any scheme that would automatically block migrants being granted asylum in the UK, with British officials also required to be in charge of processing claims.

This is not the first time the party has looked at such an approach.

In the early 2000s, Lord Blunkett and the Blair government were believed to be in talks with Tanzania about the possibility of housing asylum seekers in the country while claims were processed in the UK.

Lord Blunkett told the paper: “What’s absolutely crucial is who is doing the processing and that they’re allowed back into the country. Without it, you’re merely transferring the problem on to somebody else. But if British officials are doing the processing, then you’ve got a scheme that fits with the conventions.”

But Mr Tomlinson, the minister for Countering Illegal Immigration, said the plan would make it more attractive for migrants to come to the UK.

“This Labour policy is not a deterrent to stop the boats, it just throws open the front door to Britain, increasing immigration,” said.

“The National Crime Agency says that only a deterrent will stop the boats. Rishi Sunak’s Rwanda plan is a deterrent, it will stop the boats but Labour have voted against it.

“While Labour want open borders, the Conservatives are taking the long-term decisions to bring illegal immigration down.”

It comes as Sir Keir and his frontbench team enter a crucial period, with a general election likely to be less than 12 months away.

The Conservatives have sought to make tackling illegal migration a crunch issue, with stopping the boats one of Mr Sunak’s “five priorities”.

Just under 30,000 migrants have crossed the English Channel in 2023.

In 2022, 45,755 people made the crossing, the highest number since figures began to be collected in 2018.