WASHINGTON - The United States demanded on Tuesday that Myanmar let humanitarian groups visit people arrested in recent protests against fuel price increases, citing unspecified reports they have been brutally beaten.

More than 150 people have been arrested since Aug. 19, when the fuel protests began in Myanmar. The military has ruled the country, formerly known as Burma, for the past 45 years, and the authorities have long been accused of human rights abuses.

"We are concerned for the well-being of the more than 150 Burmese citizens detained since Aug. 19 for their participation in a series of peaceful protests against dramatically increased fuel prices in Burma," U.S. State Department spokesman Sean McCormack said in a statement.

"Multiple reports indicate that many of these protesters have been brutally beaten and interrogated," he added. "We call upon the Burmese regime to allow access to prisoners by international humanitarian organizations, such as the International Committee of the Red Cross, and renew our call for the immediate release of all political prisoners."

The latest crackdown in Myanmar has been one of the harshest since the army crushed a nationwide uprising of monks, students and government workers in 1988, when around 3,000 people are thought to have been killed.

The United States has labeled 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.