YANGON, June 3 (Reuters) -- The trial of Myanmar opposition leader Aung San Suu Kyi was delayed again on Wednesday after a court in the army-ruled country agreed to hear an appeal of an earlier decision barring three of her defence witnesses.

The Nobel laureate's trial on charges she violated her house arrest was to have final arguments on Friday, paving the way for a widely expected guilty verdict and a prison sentence of up to five years.

But the final hearing was postponed after the Yangon Division Court agreed on Wednesday to hear an appeal to include testimony from the rejected defence witnesses, her lawyer Nyan Win said.

"The final argument scheduled for June 5 has been adjourned until a later date," he told Reuters after the appeal hearing.

Suu Kyi, 63, faces three to five years in prison if found guilty of breaking the terms of her house arrest by allowing an American intruder to stay for two days after he swam to her home on May 4.

She has spent more than 13 of the past 19 years in some form of detention, much of it a virtual prisoner inside her home on Yangon's Inya Lake.

A lower court rejected three of Suu Kyi's four defence witnesses on May 27, including two senior members of her National League for Democracy (NLD). The prosecution was allowed 23 witnesses, but called only 14.

Activists said it was latest attempt by the regime to sabotage Suu Kyi's defence since her trial in Yangon's Insein prison began on May 18.

She is accused of violating her house arrest under Section 22 of a security law protecting the state from "subversive elements". Her lawyers argue that section is no longer valid because it is based on a constitution abolished years ago.

Her two female housemates and the American intruder, 53-year-old John Yettaw, are charged under the same law.

Yettaw, a Falcon, Missouri resident, has told the court God sent him to warn Suu Kyi she was going to be assassinated by "terrorists".

Suu Kyi has denied any prior knowledge of his plans and blamed the incident on a security breach, for which no officials have been punished.

The American is also accused of immigration violations and breaking a municipal law against swimming in Inya Lake.

The West has condemned the "show trial" as a ploy to keep the charismatic leader of the NLD in detention during the junta's promised elections next year.

Critics say the polls, part of the junta's seven-step "roadmap to democracy", will entrench nearly a half century of military rule in the former Burma. (Reporting by Aung Hla Tun; Writing by Darren Schuettler; Editing by Jerry Norton)