US West Texas Intermediate crude futures were up 15 cents at $47.13 a barrel.

The US dollar retreated from Monday's two-week high as investors looked ahead to jobs data this week that Federal Reserve Vice Chair Stanley Fischer has said will be important to whether the US central bank raises interest rates soon.

A weaker greenback makes oil purchases for countries with other currencies cheaper, potentially spurring demand for the fuel.

Yet concerns of a successful outcome to September talks among Opec members about a production freeze continued to weigh on markets.

"There's a feeling that the Opec production freeze talks might result in something positive, but it's just talk," said Robert Nunan, risk management director at Mitsubishi Corporation.

Saudi Arabian Energy Minister Khalid Al-Falih tempered expectations that the world's major oil producers would look to freeze production next month, telling Reuters on Thursday that the "market is moving in the right direction" already.

"Either way, despite some increases in Saudi Arabia and Iraq, Opec production seems to be flattening with the outages in Libya, Nigeria and Venezuela, knocking out about some 3 million barrels of daily production and no one is holding their breath they'll return soon," said Nunan.

Nigerian rebels pledged to end hostilities against its oil and gas industry, which they repeatedly attacked earlier this year knocking reducing the Opec member's output by 700,000 barrels per day to 1.56 million bpd.

"We promise to fight more for the Niger Delta, if this opportunity fails," the Niger Delta Avengers said in a statement received by Reuters on Sunday.