Four additional men deported from the United States have arrived in Eswatini, a lawyer and prison official confirmed on Thursday, as Washington expands its third-country deportation programme.

The four—two Somalis, a Tanzanian, and a Sudanese—arrived late Wednesday at Matsapha Maximum-Security Correctional Centre outside the capital, a prison officer said. "They are in perfect health**,”** and are undergoing orientation, the official added.

They join 15 others sent to the tiny southern African kingdom last year under US deals with several African nations to accept undocumented migrants.

The facility expects around 140 more deportees.

Controversy and legal challenge

According to a Human Rights Watch document, Eswatini agreed to accept 160 deportees in exchange for approximately US$5.1 million to build border management capacity.

Authorities say they hold migrants only while arranging repatriation.

Lawyers and civil society groups have challenged the detentions in court, arguing that deportees are held "indefinitely" without charges.

Equatorial Guinea, Ghana, Rwanda, and South Sudan have also accepted US deportees under similar arrangements.