US President Barack Obama has called on Myanmar's military rulers to immediately and unconditionally release democracy leader Aung San Suu Kyi.

Aung San Suu Kyi earlier told a court that she did not violate her house arrest during an incident in which a US man swam to her house.

'I didn't,' the Nobel peace prize winner replied when a judge asked her whether she had breached the terms of the restriction order under which she is detained.

Aung San Suu Kyi is the long-standing figurehead of the opposition movement in Burma, officially known as Myanmar.

The trial is being held at the court in the Insein jail.

She took the stand this morning for the first time since Burma's military regime charged her after US man John Yettaw swam across a lake to reach her house on 4 May and spent two days there.

'I didn't know about it (Mr Yettaw's visit) immediately. I was informed about it at 5am. My assistant told me that a man had arrived,' the 63-year-old told the court.

Ms Suu Kyi faces up to five years in jail if she is convicted.

She has spent 13 of the last 19 years in detention.

Ms Suu Kyi's house arrest order expires tomorrow and the 63-year-old is widely expected to be found guilty.

Police Brigadier General Myint Thein said authorities had considered freeing Ms Suu Kyi after her detention order ran out.

General Thein said Ms Suu Kyi allowed him to stay for two days, 'talked to him, provided him with food and clothes'.

'These things infringed on existing law and we unavoidably and regretfully had to take legal action against her,' the general told a group of 55 diplomats and Burmese journalists.

Nyan Win, one of her lawyers, complained they were unable to prepare a defence with her.

He said: 'It could be they have already written the verdict.'