The UK government plans to start sending asylum seekers to Rwanda within "weeks", the Prime Minister's policy chief has said. 

The plans by the Home Office would see "illegal" asylum seekers detained and deported to the African nation and has resulted in widespread criticism. 

Boris Johnson said he "expects" the scheme, meant to curb Channel crossings, to be challenged in courts. 

Andrew Griffith, the director of policy at No 10, said it is hoped the scheme will be operational in “weeks, or a small number of months”.

"It doesn't require new legislation, we think we can do this under the existing conventions," he told BBC Newsnight.

“And therefore this should be possible to be implemented and operationalised in weeks, or a small number of months. So we are ready to go in that sense.”

On Thursday, protesters wielding signs with the message “refugees welcome here” gathered outside the Home Office, declaring their intention to “fight back” against the move.

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Charities condemned the plans as “cruel and nasty”, claiming they would fail to address the issue and cause more “suffering and chaos”, while criticising Rwanda’s human rights track record.

But Mr Johnson insisted the scheme was not “draconian and lacking in compassion”.

Giving a major speech in Kent, he said the agreement was “uncapped” and Rwanda would have the “capacity to resettle tens of thousands of people in the years ahead”.

He said the partnership would be “fully compliant with our international legal obligations”, while insisting Rwanda was “one of the safest countries in the world”.

“But nevertheless, we expect this will be challenged in the courts,” Mr Johnson added, as he hit out at what he called a “formidable army of politically motivated lawyers”.

Labour leader Sir Keir Starmer called the plans “unworkable”, “extortionate” and an attempt to distract from Mr Johnson being fined for breaching his own pandemic laws.

The deal with Rwanda is understood to effectively be a fresh removals arrangement, where those deemed by the Government as inadmissible under UK asylum rules will be relocated.

It is thought the East African nation’s government will process the claims and those who are successful will be provided Rwandan refugee status.

This would be different from plans to offshore processing of UK asylum claims, which would involve sending migrants to another country or location while their applications are determined and then returned once approved.