LONDON (AP) — The British government said Tuesday that it plans to send a first group of asylum seekers to Rwanda in two weeks under a controversial deal with the east African country.

But legal challenges mean it is far from certain whether the flight scheduled for June 14 will take place.

The Home Office said it had begun sending formal “removal direction letters” to an unspecified number of people, including some who had arrived in Britain across the English Channel on small boats. The letters are the last administrative hurdle to the deportations, but people who receive them can challenge them in court.

“While we know attempts will now be made to frustrate the process and delay removals, I will not be deterred and remain fully committed to delivering what the British public expect,” Home Secretary Priti Patel said.

Under a deal announced last month, Britain plans to send migrants who arrive in the U.K. as stowaways or in small boats on a one-way trip to Rwanda. There the migrants’ asylum claims will be processed, and if successful, they will stay there.

U.N. officials say such a move violates the international Refugee Convention, and human rights groups call the deal — for which the U.K. has paid Rwanda 120 million pounds ($158 million) upfront — unworkable, inhumane and a waste of British taxpayers’ money.

The British government is seeking to distinguish between refugees who arrive by authorized routes, such as programs to help people fleeing Afghanistan or Ukraine, and those it says arrive by illegal means, including Channel crossings run by people smugglers.

More than 28,000 migrants entered the U.K. across the Channel last year, up from 8,500 in 2020. Dozens have died, including 27 people in November when a single boat capsized.