In his opening address of a rare OPEC summit, Venezuelan President Hugo Chavez warned the United States on Saturday that oil prices would further surge if the US contemplates an attack against his country or Iran. Minutes after Chavez declared that the Organization of Petroleum Exporting Countries should "assert itself as an active political agent," Saudi King Abdullah appeared to rebuke the Venezuelan, insisting that "OPEC has always acted moderately and wisely." "Oil is an energy for development, it should not become a tool for conflict and emotions," said the king of conservative Saudi Arabia in an apparent response to the leftist leader. The OPEC summit opened Saturday in the Saudi capital, with heads of states and delegates from 12 of the world's biggest oil-producing nations. Chavez warned that the US should not target OPEC members for foreign policy reasons. "If the United States attempts the madness of invading Iran or attacking Venezuela again, the price of oil is probably going to reach $200, not just $100," Chavez told delegates. While Iran has been in a standoff with the US over its nuclear program, Chavez is a bitter antagonist of US President George W. Bush. "We are witnessing constant threats against Iran," Chavez said. "I think OPEC should strengthen itself in this capacity and demand respect for the sovereignty of our nations, if the developed world wants a guaranteed supply of oil," he said. King Abdullah, a close US ally whose country is the world's largest oil producer, replied in his speech that OPEC has "two essential objectives" since its creation: "First to defend the interest of its members, and second to protect the international economy from sudden shake-ups in oil prices and supplies." "Those who say that OPEC should be a manipulative monopoly are ignoring the fact that OPEC had always behaved moderately and wisely," Abdullah said. It was the third full OPEC summit since the organization was created in 1960. The run-up to the meeting was dominated by speculation over whether OPEC would raise production following recent oil price increases that have closed in on US$100 per barrel. US Energy Secretary Samuel Bodman called on OPEC to increase production earlier this week, but cartel officials have said they will hold off any decision until the group meets next month in the United Arab Emirates. They have also cast doubt on the effect any output hike would have on oil prices, saying the recent rise has been driven by the falling dollar and financial speculation by investment funds, rather than any supply shortage. Saudi Arabia opposed a move by Iran on Friday to have OPEC include concerns over the falling dollar included in the summit's closing statement after the weekend meeting. Following Chavez, the Saudi king also tried to redirect the OPEC opening session to the summit's agenda, announcing a move by the oil cartel to support environmental efforts. "I wish to announce that the Saudi government has put US$300 million (â‚¬204.76 million) in a program to finance scientific research in the fields of energy, environment and climate," Abdullah told delegates. He called on other OPEC nations to contribute to the fund, which will be geared at promoting a better environment.