In a formal notice to Congress, President Barack Obama said that he was renewing sanctions that would otherwise have expired this month because Myanmar, also known as Burma, was taking actions "hostile to US interests."

Obama, using language nearly identical to previous years, criticized actions by the regime including the "large-scale repression of the democratic opposition" in deciding to extend the measures that limit trade with Myanmar.

The Obama administration in 2009 launched an engagement drive with Myanmar, concluding that the previous Western policy of trying to isolate the regime had failed.

But the administration has said that it is disappointed with the results of the dialogue and rejected calls by some Asian nations to ease sanctions on Myanmar after it last year held elections, which were widely criticized.

Myanmar's President Thein Sein, in a message read on state television Monday, said that the government was reducing all prisoners' sentences by one year and commuting the death penalty to life imprisonment.

The United States and democracy activists have called for a broader amnesty in Myanmar, where many political opponents are held under vague laws for double-digit terms.

"We would just reiterate our call that all political prisoners should be released immediately," US State Department spokesman Mark Toner told reporters. 

The regime last year released Nobel Prize-winning opposition leader Aung San Suu Kyi, who has spent most of the last two decades under house arrest. But human rights groups say more than 2,000 other political prisoners remain.