LONDON  - British interior minister Suella Braverman will visit Rwanda this weekend to discuss an agreement where Britain will relocate migrants who arrive without permission, as she doubles down on a plan that has been mired in legal challenges and controversy.

Britain agreed to send tens of thousands of migrants more than 4,000 miles away (6,400 km) to Rwanda as part of a 120 million pound ($146 million) deal last year, though no flights have taken off as opponents challenge the policy in the courts.

The partnership is a major part of Britain's plans to detain and deport asylum seekers arriving in small boats across the Channel, a proposal some charities say could be impractical and criminalise the efforts of thousands of genuine refugees.

Braverman will meet Rwandan President Paul Kagame during the trip, and said that the removal of migrants to Rwanda could be put into action shortly.

"I am visiting Rwanda this weekend to reinforce the government's commitment to the partnership as part of our plan to stop the boats and discuss plans to operationalise our agreement shortly," she said in a statement.

The partnership was announced in April, but the first deportation flight was blocked by an injunction from the European Court of Human Rights.

London's High Court then ruled it lawful in December but opponents are seeking to appeal that verdict in April and it could yet go to Britain's Supreme Court later in the year.

Braverman has robustly defended her approach, described her opponents as "naive do-gooders." Opposition parties and charities have described the governments plans on immigration as unethical and unworkable.

After a record 45,000 migrants arrived in Britain last year on small boats, Prime Minister Rishi Sunak has said that finding a solution is one of his top priorities. Britain spends more than 2 billion pounds a year to accommodate them, and has tendered a $95 million contract to transport them to countries like Rwanda instead.

($1 = 0.8225 pounds)

(Reporting by Alistair Smout; Editing by Mark Porter)