Ban Ki Moon, the UN Secretary-General, asked the leader of Burmese junta to release the detained democracy leader, Aung San Suu Kyi, today but was refused the chance to meet her in an unpromising start to an important two-day visit.

In a risky move, which will be denounced by human rights groups if it fails to achieve results, Mr Ban travelled to Naypyidaw, the junta’s remote new capital, to meet General Than Shwe.

The meeting with Ms Suu Kyi, which would have been at the heart of his visit, appeared to have been vetoed by the general because of her continuing trial over a bizarre visit by an eccentric American wellwisher. “I told him that I wanted to meet her but he told me that she is [on] trial,” Mr Ban told reporters afterwards. “But I told him that this is my proposal, and this is important, and I'm waiting for their reply.”

Mr Ban had said on his arrival that he was engaged on a “very tough mission” but promised to press the case for releasing Ms Suu Kyi and more than 2,000 other political prisoners in Burma. “I'm going to urge [them] to accelerate their political process,” he said, “and release all political prisoners, including Aung San Suu Kyi … The genuine will of the Myanmar people should be reflected.”

The continuing uncertainty about his chances of meeting her in person underlines the potential for embarrassment for Mr Ban. If he comes away without a significant compromise by the regime, he risks undermining the UN’s authority in a country where neither punitive sanctions nor diplomatic engagement have brought any obvious improvements.

Ms Suu Kyi’s trial had been scheduled to resume today after a month-long adjournment but after Mr Ban’s arrival it was announced that it had been delayed for another week. She and two of her woman companions are accused of violating the terms of her house arrest by giving food and shelter to John Yettaw, the eccentric American who swam uninvited to her lakeside home in Rangoon after he had visions of her assassination in a dream.

She has spent more than 13 years under house arrest since 1989, when her political party, the National League for Democracy (NLD), won an overwhelming victory in an election that has never been acknowledged by the Government. Since her arrest in May she and her companions have been held in a guesthouse in the grounds of Rangoon’s notorious Insein prison, where their trial has also been conducted.

Apart from two days when journalist and diplomats were allowed to attend, the trial has been held in closed court. On Monday the Burmese Supreme Court rejected a request by her lawyers to allow two opposition politicians to speak in her defence.

If convicted Ms Suu Kyi would face a prison sentence of up to five years in jail, rather than under house arrest – conveniently for the junta, this would take her out of circulation until well after the election, which it promises to hold next year.

The constitution under which the election will be held has been denounced as unfair by foreign governments and Ms Suu Kyi’s National League for Democracy because it guarantees a place in Burmese politics to the military. It also excludes anyone with foreign relatives – a clause apparently aimed at Ms Suu Kyi, whose has two sons by her late British husband.

“I was assured that the Myanmar authorities will make sure that this election will be held in a fair and free and transparent manner,” Mr Ban said, a statement which will do little to placate those who have been urging him to take a much tougher and angrier line with the recalcitrant regime.

Mr Ban also urged dialogue between the NLD and the State Peace and Development Council, as the junta styles itself. On his last visit to Burma, in the aftermath of the devastating Cyclone Nargis in May last year, he achieved a personal triumph when General Than Shwe agreed to allow foreign aid workers into the disaster area after weeks of resistance.

But he played down expectations of success on this week’s visit. “I'm visiting Myanmar with certain uncertainties,” he said. “We must try our best to bring changes. I'll do my best. I do not believe my visit should be a make-or-break event.”

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