“He will arrive here on Friday for a three-day visit,” said a government official who requested anonymity.

Webb, who is chairman of the East Asia and Pacific Affairs Committee, is due to travel to the junta’s headquarters in Naypyitaw to meet with military leaders, but it is uncertain whether he will meet with the regime’s head, Senior General Than Shwe, the source said.

Webb, a past proponent of change in US foreign policy towards Myanmar, would be the first US senator to visit Myanmar in more than ten years.

He is expected to seek the release of US national John William Yettaw, 54, who was on Tuesday sentenced to seven years in prison with labour for swimming to the house-cum-prison of opposition leader Aung San Suu Kyi on May 3 on a mission to warn her of an assassination attempt he had envisioned.

Suu Kyi was sentenced by the same court to three years in prison, which was swiftly commuted to 18 months under house arrest by Than Shwe.

Myanmar pro-democracy groups have questioned the timing of Webb’s visit and cautioned him not to become a tool of the ruling regime.

“We are concerned that the military regime will manipulate and exploit your visit and propagandize that you endorse the trial of Daw Aung San Suu Kyi and the imprisonment of over 2,100 political prisoners, their human rights abuses on the people of Burma and their systematic, widespread and ongoing atrocities against the ethnic minorities,” said the joint statement sent to the US embassy in Yangon by the All Burma Monks Alliance, 88 Generation Students and All Burma Federation of Student Unions.