Jakarta – Indonesia has accused Australia's opposition party of interfering in its sovereignty following a call by the party's president for a self-determination ballot in Irian Jaya, a report said Thursday.

"West Papua or Irian Jaya is part of Indonesian territory, by an act of international law," the state Antara news agency quoted Justice and Human Right Minister Yusril Ihza Mahendra as saying.

Mahendra, speaking in the Australian capital, Canberra, was commenting on a memorandum of understanding signed by Australian Labor Party (ALP) president Greg Sword with Irian Jaya separatist leader Jacob Rumbiak on Tuesday.

The memorandum called for the United Nations to organize a plebiscite on the future of the restive province, which is on the western half of New Guinea island bordering independent Papua New Guinea.

Sword is also the vice-president of the Australian Council of Trade Unions (ACTU). "If the Australian Labor Party and Labor Council take it up as a problem, it is interference in Indonesia's sovereignty," Mahendra said.

Citing a 1969 UN-approved vote in Irian Jaya, after which the UN General Assembly recognised it as part of Indonesia, Mahendra said any claims Irian Jaya should not be part of Indonesia "run counter to international law."

Sword's call flew in the face of the ALP's official policy on Irian Jaya and prompted a harsh rebuke by the party's foreign affairs spokesman, Laurie Brereton. "Mr Sword's advocacy of a UN-sponsored referendum has not been well thought through and is unlikely to contribute to any lessening of tension in West Papua," Brereton was quoted as saying in Australia's Age newspaper. He called the move "ill-considered" and a threat to relations between Indonesia and Australia.

Indonesian leaders, still smarting over Australia's high-profile role in East Timor's moves to independence last year, have several times recently accused Australia of supporting Irian Jaya's separatist movement. In response Australian leaders have repeatedly made reasssurances of their support for "Indonesia's territorial integrity."

Indonesian sovereignty over what was Dutch New Guinea was formalised with the 1969 Act of Free Choice, the validity of which is contested by separatist leaders.

Years of neglect by the central government, the perceived exploitation of the province's rich mineral reserves and military brutality have fed anti-Indonesian feelings in Irian Jaya.

Separatist calls have mounted in recent years, peaking with a mass people's congress in June this year in which a resolution was passed demanding Jakarta recognise its independence.