The Mexican activist,Gustavo Castro, announced the suit at the Inter-American Commission on Human Rights through his lawyers, who said Honduras had acted unconstitutionally and in violation of Castro's human rights.

Castro, an environmental activist, witnessed the March 2016 murder by two gunmen of Berta Caceres, a high-profile Honduran activist who led an indigenous association fighting the construction of a hydroelectric dam in Honduras.

The Mexican, who was wounded in the attack, was held by Honduran officials when he tried to fly back to Mexico. He was taken to the Mexican embassy in the Honduran capital for weeks of questioning before being permitted to leave the country.

Seven people have been arrested in relation to the crime, including an employee of the company building the dam, and a Honduran seized in Mexico last week.