SYDNEY (Reuters) - A second group of about 30 refugees held in Australian-run detention centers on South Pacific islands will leave soon for resettlement in the United States under a controversial refugee swap deal, a U.S. official said on Tuesday.

The first group of 22, including men from Bangladesh, Sudan and Rohingya Muslims from Myanmar, left one of the camps on Manus Island in Papua New Guinea on Sunday. They were due to board a plane from Port Moresby to Manila later on Tuesday on their way to the United States.

Beverly Thacker, public affairs officer for the U.S. embassy in Papua New Guinea, said a second group would leave soon from the other center on the tiny island of Nauru.

“I understand the group of refugees from Nauru will fly via Port Moresby before traveling on to the United States on Wednesday,” she said.

Australia agreed on a deal with former U.S. President Barack Obama late last year under which up to 1,250 refugees held in the Australian camps will be offered residency.

In return, Australia agreed to resettle several dozen Central American refugees. Those refugees were expected to arrive in Australia within weeks.

U.S. President Donald Trump has described the deal as “dumb” but begrudgingly said he will honor it.

Concerns persist, however, that many of the refugees in the Australian-run camps will not be offered U.S. resettlement, with the Trump administration vowing that only those who satisfy “extreme vetting” will be approved.

Nearly 2,000 men, women and children are held on Manus island and Nauru, where most of them have been awarded refugee status.

Despite their refugee status, many of those on Nauru and Manus island have been held for four years in conditions widely criticized by the United Nations and human rights groups.

Under Canberra’s hardline immigration policy, asylum-seekers intercepted at sea trying to reach Australia are sent for processing on Manus island and Nauru and are told they will never be settled in Australia.