Two Malawian prisoners serving life sentences there for treason were convicted by a court that ignored normal rules of law and fairness, according to legal documents released Wednesday by Amnesty International.

The two, former minister of justice Orton Chirwa and his wife Vera, opponents of President Hastings Banda who say they were kidnaped from exile and forcibly returned to Malawi in 1981, were tried by a traditional court that lacked proper jurisdiction and were denied the right to a lawyer and to call witnesses on their behalf, according to the documents. The Amnesty International documents include texts of the judgments by the traditional court that convicted the Chirwas and the national appeals court, which upheld the verdict.

The documents also show that the courts admitted as valid evidence confessions that the Chirwas refused to sign and handwritten political statements they alleged were forgeries and that were verified by a handwriting "expert" who was the chief investigating officer in the case.

The appeals court review noted of the original trial, "The record is littered with unnecessary abuse, which is not part of the tradition or law. Some of the trial court's rulings are wrong in law. . . . The court raised numerous doubts and made some extraordinary findings." Nonetheless, the appeals court upheld the convictions, citing unwritten "custom" and "traditions" as justification.

"The case is significant because it illustrates the ways in which courts may abandon well-tried principles of due process of law and order to secure the conviction of a political opponent," said South African legal scholar John Dugard, an Amnesty International representative who was denied the right to attend the supposedly public trial by Malawian authorities but who reviewed the court records for the London-based human rights organization.

The Chirwas, who have been designated by the organization as "prisoners of conscience," were condemned to death by the court in May 1983. Banda commuted their sentences to life imprisonment last June after an international outcry. They remain in prison, were Amnesty said their health has deteriorated seriously.

Malawian officials have denied that the Chirwas were kidnaped from neighboring Zambia, contending instead that the couple was captured after entering Malawi illegally while plotting to overthrow the Banda government. The authorities also contend that the two received a fair trial under Malawian law.

Orton Chirwa, who is in his mid-sixties, was Banda's first attorney general and justice minister after Malawi became independent in 1964. His wife Vera, 52, was Malawi's first woman lawyer and has lectured in law at several African universities.

After falling out with Banda, the two left Malawi in late 1964 and settled in neighboring Tanzania, where in 1977 they established the Malawi Freedom Movement, which was critical of the Banda government. The government, which has banned all political organizations except for the country's ruling party, contends that the movement sought to depose Banda, a charge the Chirwas denied.

The Chirwas were arrested in December 1981, purportedly while on a Christmas visit to a daughter in northern Zambia. They were convicted of treason in May 1983, a conviction upheld on appeal last February. They were tried by a traditional court, set up to hear low-level civil cases and misdemeanors, where usual rules of evidence and other internationally recognized legal procedures do not apply.

Amnesty International, contending that the organization the Chirwas founded was nonviolent and a free expression of their political rights, has called for their immediate release.

Fumbani Chirwa, the Chirwas' son, was arrested with them and detained without charge for more than two years before his release last February. The Chirwas have a daughter who lives in Hyattsville and has helped organize the international campaign to free her parents.