The Burmese Freedom and Democracy Act, referring to Myanmar's former name, renews a sanctions regime imposed since 2003 over the suppression of the opposition led by Nobel Peace laureate Aung San Suu Kyi.

She has been held under house arrest in Yangon for most of the past 18 years.

The new Block Burmese Jade Act is aimed at stopping precious stones, including jade and rubies, from entering the US via countries such as Thailand, China, Taiwan, Malaysia and Singapore.

Gemstones are Myanmar's third largest source of income and the new law is aimed at depriving Myanmar's ruling generals of hundreds of millions of dollars in annual revenue.

The bill also makes Myanmar's generals and their families ineligible for visas to the United States and enhances existing financial sanctions against the government.