Mr Ban talked for two hours with reclusive Senior Gen Than Shwe in an ornate reception hall - complete with an indoor waterfall - in Naypyitaw, the junta's remote, newly built capital.

It was a rocky start to what the UN chief predicted would be 'a very tough mission' to win freedom for Aung San Suu Kyi, the 64-year-old Nobel Peace Prize laureate who has been detained by the junta for nearly 14 of the past 20 years and is now on trial charged with violating her house arrest.

Mr Ban emerged from Friday's meeting saying he still hoped to meet the Suu Kyi before he leaves the country on Saturday night.

'I told him that I wanted to meet her, but he told me that she is (on) trial,' Ban told reporters after meeting with Than Shwe.

'But I told him that this is my proposal, and this is important, and I'm waiting for their reply.'

It was Mr Ban's second visit to Myanmar since Cyclone Nargis devastated much of the country last year.

His first visit managed to persuade the military government to ease access for hundreds of foreign aid workers who had been restricted from entering cyclone-affected areas. He also oversaw a conference that raised up to US$150 million (S$225 million) in emergency relief funds.

However, the UN has been unable to budge the junta on its refusal to free its estimated 2,100 political prisoners, including Suu Kyi.

Shortly after the UN chief arrived Friday, the court presiding over Suu Kyi's widely criticized trial announced an adjournment until July 10. The trial had been set to resume after a monthlong delay.

In May, she was charged with violating the terms of her house arrest when an uninvited American man swam secretly to her lakeside home in May and stayed for two days. She has pleaded not guilty and faces five years in prison if convicted. -- AP