The widely criticized proceedings were expected to end on Friday with the defense lawyers and the prosecution presenting final arguments. But the diplomat said only the defense presented its argument on Friday.
The diplomat spoke on condition of anonymity, citing diplomatic protocol.
Suu Kyi, 64, is charged with violating the terms of her house arrest by harboring an uninvited American man who swam to her lakeside home and stayed for two days.
“She was well and in good spirits,” said the diplomat. “She was seen joking with her lawyers.” The verdict is expected sometime next month, and Suu Kyi faces up to five years in prison. The lawyer of the American visitor, 53-year-old John Yettaw, will also present a statement on Monday. Yettaw was charged with trespassing.
The defense has not contested the facts of the case but argues that the relevant law has been misapplied by the authorities and that Suu Kyi was charged under a constitution abolished two decades ago. They also assert that the security guards who ensure Suu Kyi remained inside her compound should be held responsible for any intrusion on her property.
Security was tight around Insein prison -- where Suu Kyi is being held and the trial is ongoing _ with roads blocked with barbed wire barricades manned by police. Seven truckloads of riot police were deployed around the compound and pro-government supporters were seen gathering near the area.
Diplomats from Britain, France, Germany, Norway and Italy who had earlier requested access were allowed into the courtroom for Friday's session, a diplomat said on condition of anonymity citing protocol. It was the third time during the mostly closed-door trial that such access has been granted.
The resumption of the trial came after US, European and Asian officials _ including the top diplomat from Myanmar -- wound up a conference Thursday in neighboring Thailand that put Myanmar's human rights record in the spotlight.