Oil prices climbed slightly in thin Easter holiday trading on Monday, adding to gains in recent weeks as optimism holds that a production freeze among major producers may be implemented.
Brent crude futures were up just 9 cents at $40.53 per barrel at 1107 GMT. Last week, the contract fell 76 cents, or nearly 2%, in its first decline in five weeks.
U.S. crude's front-month contract was up 20 cents at $39.66 a barrel.
Oil prices have risen about 50% from multi-year lows hit in January on glut worries.
Prices have been supported by disruptions to oil supplies in Nigeria and Iraq and plans by major producers to freeze their output at January levels.
Members and non-members from the Organization of the Petroleum Exporting Countries (OPEC) are due to meet in the Qatari capital Doha on April 17 to discuss the plan.
"There is going to be pressure on the participants in the meeting to ensure they achieve something. Otherwise they risk the support-market sentiment that we are seeing now dissipate rapidly," said Victor Shum, senior oil and gas analyst at IHS in Singapore.
So far, 10 countries have confirmed their attendance at the meeting, with only OPEC-member Libya saying it will not attend.