WASHINGTON: US President Barack Obama on Tuesday extended sanctions against Myanmar, including a ban on gem imports, as the military regime prepares a verdict for democracy leader Aung San Suu Kyi.

The White House in a brief statement said Obama signed into law a bill overwhelmingly approved by Congress that would prolong sanctions on all imports from Myanmar for three years. The sanctions were due to expire this week.

The measure also confirms a ban on US sales of Myanmar's gems, which had until last year still entered the US market due to a now-plugged loophole.

Congressman Joseph Crowley, who introduced the bill in the House, said that the junta in Myanmar, earlier known as Burma, "must be stopped." "We must show the military regime currently ruling with an iron fist in Burma that there are consequences for their actions," said Crowley, a New York lawmaker from Obama's Democratic Party.

He denounced Myanmar's "brutal campaign against its own people," which has triggered a major refugee problem, along with the regime's refusal to let UN chief Ban Ki-moon even see Aung San Suu Kyi on a recent visit.

Aung San Suu Kyi has been in jail or under house arrest for 13 of the last 19 years since the junta refused to recognise her party's landslide victory in Myanmar's last national elections, in 1990.

A Myanmar court on Friday will deliver a verdict on the Nobel Peace Prize winner, who faces up to five years in prison over a bizarre incident in which an American man swam uninvited to her lakeside house.

Myanmar, one of the world's poorest countries, is the source of some of the world's most beautiful rubies -- a key source of revenue for the junta.

The European Union, Australia, Canada and New Zealand also have slapped sanctions on Myanmar's gems, although some Asian nations continue to buy them.