GENEVA - Three U.N. human rights experts called on Myanmar on Thursday to release more than 150 protesters detained after demonstrating against fuel price increases.

The U.N. investigators on freedom of opinion and expression, the independence of judges and lawyers, and human rights in Myanmar said the "brutal arrests" violated international human rights standards and should not be tolerated.

"It is shocking that peaceful demonstrators have received life sentences in trials without any basic guarantee of the due process of law and that local journalists were prevented from reporting on these measures," Ambeyi Ligabo, Leandro Despouy, and Paulo Sergio Pinheiro said in a joint statement.

The crackdown in Myanmar, which followed the start of fuel protests on Aug. 19, has been one of the harshest since the army crushed an uprising of monks, students and government workers in 1988, when 3,000 people are thought to have been killed.

The appeal was echoed by the U.N. High Commissioner for Human Rights, Louise Arbour, who told the U.N. Human Rights Council she had been following the suppression of the peaceful protests with growing concern.

The military has ruled the country, formerly known as Burma, for the past 45 years and authorities there have long been accused of human rights abuses.

Washington has called Myanmar an "outpost of tyranny" and imposed economic sanctions, but the junta has avoided total isolation by using its vast natural gas reserves to befriend energy-hungry China and India.