BANGKOK: UN Secretary General Ban Ki-moon delivered a stern rebuke to Myanmar's junta Saturday after the country's military ruler refused to let him meet detained pro-democracy leader Aung San Suu Kyi.

Ban said the snub by top general Than Shwe was a missed opportunity for the hardline regime to show its commitment to fostering democracy and to holding free and fair elections as promised in 2010.

But he denied that he was ending his two-day visit empty-handed, saying that the reclusive junta chief had not rejected any of his other proposals for reform including the release of political prisoners.

"I am deeply disappointed that Senior General Than Shwe refused my request for a visit to Daw Aung San Suu Kyi," Ban told reporters in Bangkok after flying out of Yangon.

He said that being able to visit her would have been an "important symbol of the government's willingness to embark on the kind of meaningful engagement that will be essential if the elections of 2010 are to be seen as credible."

"I believe the government of Myanmar failed to take a unique opportunity to show its commitment for a new era of political openness."

The refusal will spur critics of Ban's visit to Myanmar, which had been considered diplomatically risky because of its timing during Aung San Suu Kyi's trial on charges of breaching the terms of her house arrest.

The 64-year-old was transferred from her lakeside home to Yangon's notorious Insein prison in May to face trial after an American man swam uninvited to the property. She faces up to five years in jail if convicted.

Ban however said that his visit had allowed him to convey "very frankly" the international community's concerns to Than Shwe over the course of their two meetings in the bunker-like capital of Naypyidaw.

"If you use the word reject, it's only my request to meet Daw Aung San Suu Kyi. For all my proposals, I believe they will seriously consider, they have not rejected any of what I proposed," Ban said.

Rights groups had warned that his visit would be considered a major failure unless he managed to win the release of Aung San Suu Kyi, who has been detained for most of the last two decades.

Ban was kept waiting overnight in Myanmar to hear whether Than Shwe would allow him to see Aung San Suu Kyi.

Critics have accused the junta of using her trial as an excuse to keep Aung San Suu Kyi locked up for the polls. They also say the elections are a sham designed to entrench the generals' power.

In a rare public speech to diplomats and aid workers in the commercial hub Yangon, Ban earlier outlined his vision for a democratic Myanmar.

"I am here today to say: Myanmar, you are not alone. We want to work with you for a united, peaceful, prosperous, democratic and modern Myanmar," Ban said.

The UN chief also visited areas affected by deadly Cyclone Nargis in 2008. He made his first visit to the country after the disaster, when he managed to persuade the regime to accept international aid.

Aung San Suu Kyi appeared in court in Yangon on Friday but the trial was adjourned for a week because the judges had not received an earlier judgement barring two defence witnesses.

The case has sparked international outrage, with US President Barack Obama calling it a "show trial" and a host of world leaders and celebrities calling for her release.

In London, British Prime Minister Gordon Brown raised the prospect Saturday of further sanctions against Myanmar following Ban's apparently fruitless visit.

Aung San Suu Kyi has been under house arrest or in detention for 13 of the last 19 years since the junta refused to recognise her National League for Democracy's landslide victory in Myanmar's last elections, in 1990.

Ban has faced recent criticism for his softly-softly approach to the job of secretary general, but diplomats say he had hoped his quiet brand of diplomacy would work with Myanmar's generals.

Myanmar, formerly known as Burma, has been ruled by the military since 1962.