Suella Braverman has launched a full-scale attack on her old boss Rishi Sunak, a day after he sacked her as home secretary.

In a blistering letter to the prime minister, she said he had repeatedly failed on key policies and broken pledges over immigration.

Mr Sunak had adopted "wishful thinking" to "avoid having to make hard choices", she wrote.

Her broadside comes on the eve of a key ruling on the government's Rwanda plan.

On Wednesday morning, the UK Supreme Court will deliver its verdict on the lawfulness of the postponed scheme to send some asylum seekers to Rwanda to claim asylum there.

The ruling on the flagship policy will be a key moment for Mr Sunak's government, and could reignite divisions among Tory MPs over the ECHR human rights treaty.

Mrs Braverman, a leading figure on the right of the party, has previously described delivering the Rwanda plan as her "dream" and "obsession".

In her letter, the former home secretary claimed she struck a secret deal to serve in Mr Sunak's cabinet in exchange for a series of commitmentsin key areas, after Liz Truss's premiership imploded last year.

Her support, she added, had been a "pivotal factor" in allowing Mr Sunak to win the support of Tory MPs and enter No 10.

She added that she had argued within government for curbs on human rights law to ensure the Rwanda policy was not derailed by legal challenges.

But compromises from Mr Sunak during the passage of the Illegal Migration Act, she wrote, had left the policy "vulnerable" to legal challenges under the European Convention of Human Rights, even if the Supreme Court declares it lawful.

If the ruling goes against the government, she added, he would have "wasted a year" on the flagship law to stop small boat crossings, "only to arrive back at square one".

"Worse than this, your magical thinking - believing that you can will your way through this without upsetting polite opinion - has meant you have failed to prepare any sort of credible Plan B," she wrote.

A No 10 spokesman thanked Mrs Braverman for her service, but added: "The prime minister was proud to appoint a strong, united team yesterday focused on delivering for the British people."

He said the government had "brought forward the toughest legislation to tackle illegal migration this country has seen and has subsequently reduced the number of boat crossings by a third this year".

And whatever the outcome of the Supreme Court tomorrow, the prime minister "will continue that work," he said.

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