The Organization of Petroleum Exporting Countries (OPEC) has urged non-OPEC oil producing countries to pump more oil in a bid to ease soaring prices.

OPEC president Purnomo Yusgiantoro said on Monday high oil prices would hurt the economy of developing nations.

"We have asked non-OPEC countries to increase their output because high oil prices will affect developing countries," Purnomo, who is also the Indonesian minister of energy and mineral resources, was quoted Tuesday by The Jakarta Post as saying.

Purnomo said non-fundamental factors had made oil prices rise again despite the cartel's recent decision to increase output by 2.5 million barrels per day (bpd) starting Aug. 1.

He cited political tension in the Middle East as an example of one of the non-fundamental factors affecting oil prices.

"This is more related to geopolitical matters than supply-demand," he said.

The 11 members of OPEC are responsible for a third of all world oil production. The bulk of the world's oil comes from non-OPEC countries, notably Russia, Norway, Mexico and Oman.

Purnomo said OPEC would convene on July 21 in Vienna to assess the decision to increase output.

Asked if OPEC would decide to again increase output at the meeting, Purnomo said any decisions on production levels would likely take place in September.

Purnomo said OPEC's reference price of seven crude oil products could rise to about 37 US dollars per barrel in the summer, particularly if non-fundamental factors continued to affect the market.

Otherwise, OPEC's basket price could return toward its price range target of 22 dollars to 28 dollars per barrel, he said.