Whitehall sources say it could take more than a year for any treaty to be passed, with next election looming

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Rishi Sunak is attempting to finalise a new pact with Rwanda after a central plank of the British government’s immigration plans was ripped up by the supreme court.

A treaty, which would have to be ratified by the UK parliament, was being drawn up with the government in Kigali, the prime minister said.