YANGON: Lawyers for Myanmar's detained pro-democracy icon Aung San Suu Kyi lodged an appeal Thursday against her conviction on charges of sheltering an American man who swam to her lakeside house.

The Nobel peace laureate was ordered to spend 18 more months under house arrest after a court on August 11 found her guilty of breaking security laws following the bizarre incident involving US national John Yettaw.

The verdict sparked international outrage at Myanmar's ruling military junta, which has already kept the 64-year-old opposition leader locked up for 14 of the last 20 years in its bid to crush all dissent.

"We have submitted the appeal to the court," her lawyer Kyi Win told AFP.

The court would hear initial arguments from Suu Kyi's lawyers on Friday before deciding whether to officially consider the appeal, said Nyan Win, another of her lawyers and the spokesman for her National League for Democracy.

"Daw Aung San Suu Kyi is not guilty. The main person is the intruder," Nyan Win said.

Suu Kyi had insisted on her innocence during the trial held at Yangon's notorious Insein Prison, saying that she allowed former military veteran Yettaw to stay for two nights at her home because he was ill.

Yettaw was sentenced to seven years' hard labour for the stunt in early May but was freed after a visit by US senator Jim Webb last month, on what the regime said were compassionate grounds because of health problems.

The American -- who suffers from diabetes and epilepsy -- said he was on a "mission from God" to save Suu Kyi from assassination.

Suu Kyi was originally sentenced by the court to three years of "rigorous imprisonment", but in a carefully staged last-minute intervention, junta leader Than Shwe commuted the sentence to a year and half under house arrest.

Kyi Win said the appeal would focus on the fact that a 1974 constitution under which the junta had detained Suu Kyi had been superseded by a new constitution that was approved in a controversial referendum last year.

"Altogether there are 11 reasons for the appeal, but the main thing we will point out is about the constitution," he said, adding that her conviction was "not in accordance with the law."

The United Nations Security Council last month expressed "serious concern" at the verdict and the European Union extended sanctions against the junta. US President Barack Obama described the case against her as a "show trial."

Critics have accused the junta of using the charges against Suu Kyi as an excuse to keep the influential activist locked up during elections due to be held next year.

The NLD won elections in 1990 but was never allowed to take power. The military regime has handed out long jail terms to dozens of democracy campaigners in recent months.

Suu Kyi now plans to renovate her home to improve security and keep out other possible trespassers, Nyan Win said Monday.