Gains were also supported by a warning from Halliburton's executive chairman that the growth in North American rig count was "showing signs of plateauing," clouding a boom in U.S. shale oil production.
London Brent crude for September delivery was up 30 cents, or 0.6 per cent, at $48.90 a barrel by 0206 GMT after settling up 1.1 per cent on Monday.
U.S. West Texas Intermediate (WTI) crude futures were up 31 cents, or 0.7 per cent, at $46.65.
In a ministerial meeting in St. Petersburg on Monday, Saudi Energy Minister Khalid al-Falih said the Organization of the Petroleum Exporting Countries (OPEC) and non-OPEC partners were committed to extending their existing deal to cut output by 1.8 million barrels per day (bpd) beyond March 2018 if necessary.
The Saudi minister added that his country would limit crude oil exports at 6.6 million barrels per day in August, almost 1 million bpd below levels a year ago.
OPEC also agreed that Nigeria would join the deal by capping or even cutting its output from 1.8 million bpd, once it stabilises at that level from 1.7 million bpd recently. Nigeria had been exempt from the output cuts.
Russian Energy Minister Alexander Novak said that an additional 200,000 barrels per day of oil could be removed from the market if compliance with a global deal to cut output was 100 percent. The compliance was 98 percent in June, the group said.
"In our view ... these meetings were aimed at saving face and diverting the market's attention away from Iraq's poor compliance, shale's resilience, and Libya's and Nigeria's markedly higher output," Britain's Barclays bank said.
U.S. commercial crude oil inventories likely fell by 3 million barrels last week, a preliminary Reuters poll showed on Monday ahead of the data by the Industry group the American Petroleum Institute later in the day.
Industry group the American Petroleum Institute is due to release its weekly oil data at 4:30 p.m. EDT (2030 GMT) later on Tuesday.
© Thomson Reuters 2017
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