Oil prices gained Monday ahead of a meeting among crude producers scheduled on Sunday in Doha, the capital of Qatar, to discuss the output freeze.
Nawal al-Fezaia, Kuwait's OPEC governor, said last Tuesday that major oil producing countries can reach an agreement over a production freeze even if Iran does not join the move.
However, investment bank Goldman Sachs warned Monday that Sunday's meeting could fail to tighten a heavily oversupplied market.
Last week, U.S. oil companies cut oil rigs for a third week in a row to the lowest level since November 2009, oil service company Baker Hughes said Friday.
The West Texas Intermediate for May delivery moved up 64 cents to settle at 40.36 U.S. dollars a barrel on the New York Mercantile Exchange, while Brent crude for June delivery increased 89 cents to close at 42.83 dollars a barrel on the London ICE Futures Exchange.