Oil prices slumped under 67 dollars per barrel on Monday after the World Bank darkened its outlook for developing nations' economies, traders said.

The market also fell heavily as traders took profits from a recent strong run, and as the dollar strengthened against rival currencies.

New York's main futures contract, light sweet crude for delivery in July, slid 2.76 dollars to 66.79 dollars a barrel. The contract was to expire later Monday.

London's Brent North Sea crude for August fell 2.50 dollars to 66.69 dollars.

"Crude prices have continued to fall as the dollar strengthened... and after the World Bank cut 2009 and 2010 global growth forecasts for many economies, including USA, Japan and (the) euro area, dampening market sentiment," said Sucden analyst Nimit Khamar.

Prices were due for a correction after breaching the 72-dollar mark last week on concerns they were rising far ahead of a recovery in the ailing global economy, analysts said.

The World Bank slashed its forecast for developing nations' economies, estimating growth at a meagre 1.2 percent this year while warning more measures were needed for a recovery to take hold.

The forecast amounts to steep drops from the previous two years. Developing countries saw 8.1 percent growth in 2007 and a 5.9 percent expansion in 2008.

The economic weakness in the developing world after recent years of robust growth heightens the risks of social unrest and deepening poverty, the 185-nation World Bank said.

In foreign exchange market activity on Monday, the euro fell against the dollar on renewed anxiety about the state of the world economy and ahead of this week's US monetary policy meeting.

A stronger US currency makes dollar-priced oil more expensive for buyers holding weaker currencies, which in turn tends to dampen demand and pull the market lower.

Oil prices plunged from record highs of more than 147 dollars in July 2008 to around 32 dollars in December as the economic slowdown crushed demand for energy -- but the market has since rebounded.

The London-based Centre for Global Energy Studies (CGES), in its latest report published Monday, called on the OPEC producers' cartel to increase oil supplies to help cool prices, fearing that the recent rally could hamper economic recovery.

"OPEC, the holder of all the world's readily available spare oil production capacity, ought to be responding to the surge in oil prices by increasing supply," said CGES.

"More supply would obviously address the slowly tightening market fundamentals (of supply and demand), should they prove to be the cause of higher prices.

"However, rising production would also change market perceptions, indicating to speculators that OPEC is as serious about preventing sharp price rises as it was about halting last year's sharp fall.

"The fact that we have seen no hint of more production from OPEC suggests that neither the Organisation, nor its key members, has any real interest in halting the rise in oil prices," added CGES.