Energy Minister Purnomo Yusgiantoro said the government was studying whether Indonesia was already a net oil importer and thus no longer eligible to be an OPEC member, according to a Jakarta Post report.

"We have set up a team to study whether or not we should stay in OPEC," Purnomo told a parliamentary hearing in Jakarta.

"The result will be submitted to a Cabinet meeting, because there are political matters involved."

Any move to end Indonesia's 43-year membership would have to be carefully considered as it involved diplomatic ties with other OPEC members, especially the Gulf countries, Purnomo said.

Opponents of Indonesia's OPEC membership cite the country's falling oil production and periodic need to import more oil than it exports. Indonesia's oil output has fallen 5 percent annually for the last five years to less than a million barrels a day.

Indonesia's oil output has fallen 5 percent annually for the last five years to less than a million barrels a day, and the county sometimes has to import more oil than it exports.

2004 was a particularly bad year for Indonesian oil exports. Last year net crude oil exports declined from about 100,000 barrels a day in 2003 to 30,000 barrels a day and the country was a net importer of crude oil for four months, said Energy and Mineral Resources Ministry director general of oil and gas Iin Arifin Takhyan, according to a Bloomberg report.

OPEC has 11 members – Saudi Arabia, Iran, Venezuela, Iraq, United Arab Emirates, Kuwait, Nigeria, Libya, Indonesia, Algeria and Qatar.

The six Gulf region members control 63% of the world's oil reserves.

The cartel has had as many as 13 members, but Ecuador left in 1992 and Gabon exited in 1996.

Each OPEC member nations pays dues of $1.5 million euros per year to funds research and administrative staff at OPEC's Vienna headquarters.