BANGKOK — Human rights groups have called on Thai authorities to drop charges against four men being tried in a military court for expressing dissent against the country's military rulers. The four — a lawyer, a taxi driver, a university student and a man whose son was killed in 2010 anti-government protests — were arrested last month for holding a campaign to call for martial law to be revoked. The military, which took over power from a civilian government in a coup last May, has issued a ban on political gatherings of five people or more. It also has ordered security-related offenses to be handled by the military courts. New York-based Human Rights Watch said on Tuesday that the junta should stop arresting and prosecuting peaceful critics in the military courts, which are controlled by the junta. “Every arbitrary arrest shows Thailand descending deeper into dictatorial rule,” Brad Adams, the group's Asia director, said in a statement. Amnesty International issued a similar statement Monday. “It is dismaying that the military authorities are apparently backtracking on pledges that abusive martial law powers would be temporary only — there is no sign that the crackdown on rights is ending,” said Rupert Abbott, Amnesty's research director for Southeast Asia and the Pacific. The Thai Lawyers for Human Rights Center also called for the four men to be tried in a non-military court, which it said gives more justice to the accused. “The prosecution against civilians in the military court is not independent and not neutral. It is not necessary and it is clear that it is intended to be used to counteract political activists and human rights lawyers,” the group said in a statement on Monday. — AP