The opposition leader is being tried on charges that she broke the rules of her house arrest when an American man swam to her lakeside property in May, in a case has drawn fierce international criticism.

Aung San Suu Kyi's high court appeal, seeking to overturn a ban on two defence witnesses at her trial, was due to be held on June 17 but a later date will now be set, said an official speaking on condition of anonymity.

She appeared in court for a 20-minute hearing on Friday, but the closed-door prison trial was then adjourned to reconvene on June 26, the official said.

The Nobel Peace Prize winner, aged 63 and recently in poor health, faces up to five years in jail if convicted.

She believes her trial is politically motivated, her lawyer Nyan Win has said, as the charges could keep her locked up far beyond controversial elections promised for next year, in which she is barred from standing.

Some 20 members of her National League for Democracy (NLD) party on Friday sat outside Yangon's notorious Insein prison, where Aung San Suu Kyi is being held.

Western diplomats in Yangon say a string of delayed court dates is a sign that the ruling generals are seeking to stall the proceedings after being shocked by the vehement worldwide criticism of the trial.

US President Barack Obama called it a 'show trial' while the leaders of France and Germany on Thursday expressed their grave concern for the opposition leader and appealed to China and India to help.

Aung San Suu Kyi has spent 13 of the last 19 years in detention since the junta refused to recognise the NLD's landslide victory in the country's last elections in 1990. -- AFP