Sixty years after its formation, OPEC's founding members, Iran and Venezuela, have been sidelined by U.S. sanctions while its kingpin, Saudi Arabia, has shown it would rather appease Washington than risk losing U.S. support, according to current and former OPEC officials.
"All OPEC members should denounce, in words and in practice, use of oil as a political tool for imposition of sanctions and pressures on producing countries," Zamaninia was quoted as saying by the oil ministry's news agency SHANA.
Iran's share of OPEC output has nearly halved to 7.5% since 2010 while Venezuela's has collapsed to 2.3% from almost 10%, according to Reuters calculations based on OPEC data. Saudi Arabia's share, meanwhile, has risen 7 percentage points to 35%.
"We support OPEC as long as the interests of the Islamic Republic of Iran are served in a balanced way with other members. Otherwise, membership of no international organization is mandatory," Zamaninia said.
He added that he believed remaining in OPEC and strengthening the organization was currently in Iran's interests.
To tackle a drop in demand, OPEC and its allies, known as OPEC+, agreed to a record supply cut of 9.7 million bpd that started on May 1, while the United States and other nations said they would pump less.
OPEC said on Monday world oil demand will fall more steeply in 2020 than previously forecast due to the coronavirus and recover more slowly than expected next year, potentially making it harder for the group and its allies to support the market.
Zamaninia said "As long as the world economy has not returned to pre-coronavirus state, it would be impossible to offer a realistic outlook about the future of global oil demand."
(Reporting by Bozorgmehr Sharafedin; editing by David Evans and Emelia Sithole-Matarise)