Rishi Sunak’s attempts to save his flagship asylum plan have been dealt a fresh blow after it emerged Rwanda is refusing to sign a treaty that includes British involvement in its legal system.

The Prime Minister made upgrading the Rwanda deportation deal to a formal treaty the first key stage in his plan to save the scheme, which is the cornerstone of his plan to “stop the boats” of asylum seekers crossing the Channel, after the Supreme Court ruled it unlawful.

Ministers are thought to want to deploy British officials to Rwanda to convince judges the country will process asylum claims fairly.

But a source close to talks between the two countries told i the UK Government’s demands to place British officials in the country “aren’t going to be acceptable” to the Rwandan government due to concerns about sovereignty.

The setback comes amid growing Conservative discontent over ministers’ grip on both the Channel crisis and record legal immigration levels, with one source branding Mr Sunak’s No 10 “weak”.

Home Secretary James Cleverly had been due to fly to Kigali as early as last Monday to sign the treaty but i understands there are still no plans for a trip or a signing ceremony.

Rwanda believes a simple codifying of the existing UK-Rwanda memorandum of understanding on asylum is the quickest path to a deal.

iNEWS understands the UK Government believes obstacles towards signing a treaty are being overblown, however.

But Downing Street has been unable to say when the treaty will be finalised and would only say that emergency laws to declare Rwanda a “safe” country would be published in the “coming weeks”.

It comes amid increasing concern among right-wing Tory MPs that the Government will not be tough enough in its attempts to save the Rwanda plan, fuelled by Mr Cleverly’s Times interview at the weekend in which he said the policy was not “the be all and end all”.

His comments also came amid Tory anger at record net migration figures, and amid Cabinet splits on how hardline to be in response to both the Supreme Court’s judgment and on bringing down legal immigration, with Mr Cleverly signalling he was against the most hardline proposals such as ignoring the European Convention on Human Rights (ECHR).

Tory MP Jonathan Gullis told i: “The Home Secretary and I were elected on a manifesto to cut migration.

“We made a promise to the British people to stop the boats.

“He would be wise to remember this, and like the Prime Minister, he should leave all options on the table and be willing to do whatever it takes to take back control of our borders.”

A Tory source meanwhile claimed Justice Secretary Alex Chalk and Attorney General Victoria Prentis were resisting hardline proposals to ignore the ECHR backed by Immigration Minister Robert Jenrick.

“They’re in total chaos right now,” the source said.

“They physically can’t get a Bill together. Alex [Chalk] and Victoria [Prentis] have been clear on their views. Robert [Jenrick] on his.

“The lack of a Bill emerging is a symbol of how weak No 10 is at the minute”

A senior Tory MP meanwhile urged ministers to ensure a treaty was signed by early next year so there is no delay to the Government’s aim for a deportation flight to take off to Rwanda in spring.