YANGON: US Senator Jim Webb met Myanmar military ruler Than Shwe and democracy icon Aung San Suu Kyi on Saturday in an unprecedented visit that could herald a shift in Washington's tough stance against the junta.

Webb, a Democrat who is close to US President Barack Obama, became the first US official to hold talks with Than Shwe, encountering the reclusive regime supremo in his bunker-like capital Naypyidaw, officials said.

He later met Nobel peace laureate Suu Kyi at a government guesthouse near her Yangon home -- her first meeting with a foreign official since her house arrest was extended by another 18 months earlier this week.

The Myanmar regime sparked international outrage when a junta-backed court convicted Suu Kyi and US national John Yettaw over an incident in which the American swam uninvited to her lakeside home in May.

In an apparent result from the talks with Than Shwe, officials said Myanmar would likely deport Yettaw soon after Webb's departure, and without him having to serve his sentence of seven years' hard labour and imprisonment.

"Mr Yettaw is likely to be deported after the visit by the US Senator. They will not leave together," a Myanmar official said on condition of anonymity after the meeting with Than Shwe in Naypyidaw.

Webb flew to Yangon afterwards for the talks with Suu Kyi. She was driven from her crumbling mansion in a convoy comprising her car and several police vehicles, witnesses said.

She left about 45 minutes later and details of the talks were not immediately available.

He was not due to meet Yettaw, a diabetic and epileptic former military veteran who is being held at Yangon's notorious Insein Prison. Yettaw was hospitalised earlier this month after suffering a series of fits.

Dissident groups have warned that Webb's visit could be manipulated by the Myanmar government to "endorse" its treatment of Suu Kyi and the more than 2,100 other political prisoners in the country's jails.

The UN Security Council issued a watered-down statement Thursday expressing "serious concern" about her detention, while the European Union the same day extended sanctions against the junta, including the judges in the trial.

She has already spent 14 of the last 20 years in detention.

Critics have accused the junta of trumping up the charges to keep Suu Kyi locked up during elections next year, and of using the polls themselves to legitimise the grip on power that the military has held since 1962.

The junta refused to recognise the NLD's victory in elections in 1990

But the White House and State Department have both welcomed the trip, even though it is officially being made in a private capacity by Webb, the chairman of the Senate Foreign Relations subcommittee on East Asia and Pacific affairs.

The Obama administration said earlier this year that it was reviewing his predecessor George W. Bush's tough stance on Myanmar, even though Obama recently renewed sanctions against the regime.

US Secretary of State Hillary Clinton last month offered the fresh incentive of possible investment if the junta frees Suu Kyi, while warning of concerns over nuclear cooperation between North Korea and Myanmar.

Webb, a gruff Vietnam veteran, said in April that Washington should seek "constructive" engagement towards Myanmar with the aim of lifting sanctions, while admitting in July that the Suu Kyi trial made it more difficult.

Webb, 63, has written six novels and served in the late 1980s as secretary of the US Navy under Republican President Ronald Reagan.

His son served in Iraq and Webb wore his old combat boots on the campaign trail for the Senate in 2006. Webb won praise among fellow Democrats for his criticisms of George W. Bush's decision to invade Iraq in March 2003.

Than Shwe has, meanwhile, been a long-term bete noire of the United States. A former postman, he has ruled Myanmar since 1992 with an iron-fist, ruthlessly suppressing his rivals.