Oil prices tumbled close to four-year lows after the announcement, however, a clear indication of the growing belief that the world is heading for a long and painful recession in which energy use will continue to erode.

In just five months, crude has given up all the price gains made over the past four years.

Crude sank to US$40.20 after the announcement, a price not seen since the summer of 2004.

Making matters worse for OPEC, Moscow distanced itself from direct ties with the 13-nation producers' group, further dampening OPEC's hopes of coordinated production cuts that might put a floor under crude prices.

OPEC said oil ministers of the 11 nations under the group's quota system agreed to take 4.2 million barrels a day off the market, but that includes two previously announced cuts that totaled two million barrels.

- AP