The final statement of the summit of oil producing and consuming nations issued on Sunday in Jeddah called for more investment in oil production and greater financial market transparency.

The statement also said current record high oil prices and oil price volatility was harming the world economy.

"Current prices and their volatility are detrimental to the global economy, and in particular the economies of least developed countries," the statement said.

Earlier, addressing the conference, Saudi Arabia's King Abdullah launched an offensive against oil "speculators".

The king announced that Saudi output has risen to 9.7 million barrels a day, the highest figure since 1981, in a bid to defuse market tensions that have forced the price of a barrel up to almost 140 dollars.

He also said his country would give $1.5 billion to efforts to ease energy shortages in poor countries.

He told the 36-nation summit that Saudi Arabia was "very concerned" about consumers everywhere. He blamed increased oil consumption and taxes on fuel, but added: "Among other factors behind this unjust increase in oil prices is the abhorrent act of speculators seeking to undermine the market."