US Senator Jim Webb began talks with Myanmar leader Than Shwe on Saturday, becoming the first senior Washington official to meet the head of the military regime, local officials said.

The landmark encounter in the junta's bunker-like capital Naypyidaw comes days after Myanmar authorities drew international condemnation by extending Aung San Suu Kyi's house arrest.

"The US senator has started his meeting with the Senior General," a Myanmar government official said on condition of anonymity.

Webb could later on Saturday meet both Suu Kyi and John Yettaw, an American man who sparked the Nobel laureate's trial by swimming to her lakeside house in May, Myanmar officials said in a surprise development.

Suu Kyi and Yettaw were convicted by a court on Tuesday. Than Shwe commuted a prison sentence for Suu Kyi and ordered her to serve 18 more months under house arrest, but Yettaw was sentenced to seven years' jail and hard labour.

Webb, a Democrat who is close to US President Barack Obama, was due to fly to the commercial hub of Yangon where Suu Kyi and Yettaw are being held after his meeting with Than Shwe in Naypyidaw, officials said.