Yangon - United Nations special envoy to Myanmar Ibrahim Gambari arrived in Yangon Friday to pave the way for a visit by his boss, the UN Secretary-General Ban Ki-moon, expected early next month.

On this trip Gambari is expected to deliver a formal response from Ban to an invitation by Myanmar's junta to visit the country in early July, sources said.

Ban's pending visit is deemed crucial, as the ruling junta's half-hearted efforts at introducing a more democratic system have been further tarnished by a new trial against opposition leader Aung San Suu Kyi for breaking the terms of her detention last month by allowing an American national to swim into her lakeside house-cum-prison.

If found guilty, Suu Kyi faces another three to five years in prison.

Myanmar's military regime has scheduled a general election for 2010, the first since 1990. It is widely believed that junta wish Suu Kyi, 64, out of the political scene during the run-up to the polls.

Ban and many Western and Asian governments have called for the release of Suu Kyi and an estimated 2,100 other political prisoners.

Ban will be in Tokyo from June 30 to July 2 to meet government and business leaders. His itinerary after that is undecided but a visit to Myanmar is a "possibility," UN spokeswoman Michelle Montas said in New York last week.

Asked whether Ban will go to Myanmar, Montas said, "Myanmar is a possibility, but the secretary general has not decided yet."

Ban told reporters at the UN headquarters in New York early this month that he was ready to visit Myanmar.

"Promoting democratization, including the release of Daw (Mrs) Aung San Suu Kyi and other political prisoners, has been one of my top priorities and it will continue to be my top priority," Ban said then.

"When the time is appropriate and conditions are ripe, as I said many times, I'm ready to visit Myanmar. I'm working on that now."

Suu Kyi's National League for Democracy party, which won the 1990 polls, has vowed not to enter the 2010 election unless Suu Kyi is freed and steps are taken to amend the military-drafted 2008 constitution that essentially gives the army control over future elected governments.

Gambari's visit is his eighth to Myanmar and he will likely stay two days. His last visit was January 31.

On that visit he met with Suu Kyi and executive members of the NLD, but he was denied a meeting with Senior General Than Shwe. (dpa)