The US announced Tuesday it was easing economic sanctions on Myanmar after the country returned power to an elected civilian government after more than five decades under repressive military control.

The transfer of power to a civilian-led government steered by Aung San Suu Kyi and her pro-democracy party last year is a "historic milestone," said US Treasury Under Secretary Adam Szubin.

"Our actions today demonstrate our strong support for this political and economic progress," he said in a statement.

A senior US administration official said the election of a civilian government was "an objective long sought-after" by the sanctions policy.

The new actions remove restrictions on regular trade and financial activities of Americans living in Myanmar, also called by its former name Burma.

They also remove from the sanctions blacklist three banks, making it legal for Americans to do business with any bank in the country.

And seven state enterprises previously blacklisted for being part of the former milliary regime are being delisted mostly because they are now reporting to civilian ministries under the new government, the Treasury said.

The actions will remove tough constraints on Americans wanting to invest and trade in the resource-rich Southeast Asian country.

"These steps will help to facilitate trade with non-sanctioned businesses and, in turn, help the people and government of Burma achieve a more inclusive and prosperous future," said Szubin.

The Treasury left in place sanctions on a number of individuals especially associated with the previous regime, and businesses, including some gem miners.

It also said that Myanmar business tycoon Steven Law, whose late father Lo Hsing Han was a notorious heroin trafficker, remains blacklisted since 2008 along with companies in his huge Asia World business group.