Saudi Arabian Oil Minister Ali al-Naimi has sent crude prices lower with his rejection of calls for further cuts in production.

The minister, who represents the Organisation of Petroleum Exporting Countries' largest producer, said the group must wait to assess the effect of two reductions already agreed — 1.7 million barrels a day, or 2 per cent of world supply.

Crude prices have already plunged 16 per cent this year, leading Venezuela and Algeria to seek a third accord since October to cut supply.

"There is actually no real need now," Mr al-Naimi told reporters as he arrived in New Delhi for an oil conference. "I believe in a very short time it is going to improve."

OPEC agreed on a 1.2 million barrel a day cut, effective from November 1, at an October 20 meeting in Doha, Qatar.

Warmer than usual winter weather has curbed consumption in the northern hemisphere, increasing stockpiles in developed economies.

Oil fell below $US52 a barrel after Mr al-Naimi spoke, extending a four-week slump that prompted the calls for an emergency OPEC gathering before the next regular meeting scheduled for March 15.

Futures for February delivery fell as much as 3.5 per cent to $51.15 a barrel on the New York Mercantile Exchange on Monday.