A US man deported by Myanmar for swimming to the home of Aung San Suu Kyi had medical tests in Thailand Monday, as a senator who won his release said the democracy icon might ease her stance on sanctions.

John Yettaw flew out of military-ruled Myanmar on Sunday with Democrat US Senator Jim Webb, who secured the eccentric former military veteran's release by the junta from a sentence of seven years' hard labour.

Webb said Sunday that Yettaw -- who is 54 and suffers from epilepsy and diabetes -- was "not a well man" and had suffered what he called a medical episode even as he was being deported by Myanmar authorities.

"Ensuring that he is in good health and able to travel is our principal concern," Cynthia Brown, the spokeswoman for the US embassy in Bangkok, told AFP, citing privacy reasons for not giving further details.

The White House welcomed Yettaw's release and called on Myanmar to free all its political prisoners, including democracy icon Suu Kyi.

"We urge the Burmese leadership in this spirit to release all the political prisoners it is holding in detention or in house arrest, including Aung San Suu Kyi," a White House statement said, using Myanmar's old name.

Diplomatic sources said Yettaw needed to be well enough to fly back home to Falcon, Missouri. He could fly back as early as late Monday on a commercial flight but there was no confirmation yet, the sources said.

Webb declined to comment on Yettaw's situation Monday.

Yettaw was hospitalised earlier this month after suffering a series of epileptic fits while being held in Yangon's notorious Insein Prison, causing delays to the trial.

Yettaw said he intruded on Suu Kyi's house in May on a "mission from God" to warn her about a vision that she would be assassinated but his actions instead landed her with another 18 months' house arrest.

In response, the European Union tightened sanctions against Myanmar, which is already subject to a strict regime of economic and travel restrictions by the United States.

But Webb, a prominent critic of US sanctions, said that Suu Kyi might support the lifting of some measures against the junta after years of publicly discouraging foreign investment in Myanmar.

The junta allowed him to hold talks with Suu Kyi, a privilege it denied even UN chief Ban Ki-moon last month, and he also became the first top US official to meet regime leader Than Shwe.

"With respect to Aung San Suu Kyi, I don't want to take the risk of misrepresenting her views but I would say to you it was my clear impression from her that she is not opposed to lifting some sanctions," Webb said.

"I can say it was my impression from listening to her in the conversation that there were some areas that she would be willing to look at," he told a press conference after meeting with Thai officials.

He said he agreed with the stance of Myanmar's neighbours that US sanctions were not helping to effect change in the country, adding that they were merely increasing China's influence over its ally.

"My view is that we don't have any more sanctions to put on Myanmar and we need a new approach," Webb said.

Webb denied after the talks that he had offered Myanmar's rulers anything in exchange for Yettaw's freedom and said he was "hopeful" they would heed calls to free Suu Kyi to allow her to participate in elections due in 2010.

Meanwhile, Webb told CNN that regional leaders could issue a joint call for Myanmar to release Suu Kyi.

The Association of Southeast Asian Nations (ASEAN) has faced frequent criticism for taking a soft line on its most troublesome member, but Webb indicated the bloc could be about to toughen its stance.

The UN's Ban, who has repeatedly appealed to Myanmar's rulers to free Suu Kyi and other political prisoners, welcomed Webb's talks with Than Shwe and Suu Kyi and also hailed Yettaw's release, his press office said.

The US senator's visit was seen as heralding a possible softening of Washington's stance towards Myanmar, in line with previous statements by President Barack Obama's administration about reviewing US policy.

Webb was due to leave for Cambodia on Tuesday on the latest stop of a two-week Southeast Asian tour.