The defence minister has rejected calls for a UN inquiry into the death of Indonesia's leading human rights activist, following the acquittal of the only suspect in the poisoning.

Munir Said Thalib, who gained a reputation for exposing abuses by the Indonesian military in the late 1990s, was given a massive overdose of arsenic on a flight from Jakarta to Amsterdam in 2004.

His widow, who suspects the involvement of state intelligence in the murder, met with UN Special Rapporteur Philip Alston in New York last month, asking that he take over the investigation.

Defence Minister Juwono Sudarsono rejected the proposal. "We don't need international intervention," he said, adding that United Nations, foreign governments and human rights groups were welcome to express concern or offer advice about the case. "But our own legal system can handle this."

Munir became violently ill and died two hours before landing at Schipol International Airport. An off-duty pilot with the Garuda national carrier, Pollycarpus Budihari Priyanto, was accused of lacing his food with arsenic, but the Supreme Court threw out the charges last month, saying there was insufficient evidence.

The case attracted international attention, with the US House of Representatives and the European Union parliament among those calling for justice.

It is seen as a key test of whether the government of President Susilo Bambang Yudhoyono can break with the traditions of Suharto, the dictator who ruled Indonesia for 32 years until democracy riots forced him to resign in 1998.

State-sponsored killings were common during Suharto's regime and few were ever punished.

Rights groups have called on authorities to release the conclusions of a fact-finding commission that determined Priyanto had contact with an agent from Indonesia's intelligence agency. That information never surfaced in court.