Benchmark Brent crude oil LCOc1 was up 50 cents a barrel at $56.96 by 1440 GMT (9:40 a.m. ET). U.S. light crude CLc1 was up 45 cents a barrel at $53.71. Both contracts rose by around 2 percent on Wednesday.

The decline in December comes as OPEC, which controls around 40 percent of global supply, is planning to curb output in a bid to boost oil prices. The organization reached a historic deal last month with Russia and other non-members to cut global production by almost 1.8 million barrels a day starting this month.

U.S. light crude was down 20 cents at $53.86 by 0930 GMT (4:30 a.m. ET), while North Sea Brent crude was up 5 cents at $56.27 a barrel.

International Brent LCOc1 crude futures were trading down 7 cents, or 0.12 percent, at $56.02 a barrel at 0722 GMT (2.22 a.m. ET) after closing the previous session up 93 cents. U.S. benchmark West Texas Intermediate (WTI) crude oil prices CLc1 were down 8 cents at $53.82 per barrel after settling up 88 cents at $53.90 a barrel in the previous session.

The most important challenge facing Iran and all the Iranian technical and professional elite is high recovery of coefficient, he said, adding that raising the recovery coefficient by one percent will result in 700 billion barrels or let's say seven billion barrels; seven billion barrels with an oil sold for 50 dollars per barrel means 350 billion dollars more wealth for the country.

Venezuela said on Tuesday it will cut 95,000 barrels-per-day of oil production in the New Year in fulfilment of a producers' deal to reduce global output and strengthen prices.

London Brent crude for February delivery LCOc1 was down 1 cents at $55.15 a barrel by 0335 GMT (10.35 p.m. ET) after settling up 11 cents on Friday. Oil markets were closed on Monday after Christmas at the weekend. NYMEX crude for February delivery CLc1 was up 10 cents at $53.12 a barrel, after closing at a 17-month high on Friday.

Russia's output of oil products is expected to fall by about 2.5 percent in 2017 due to further work on a massive refinery modernisation programme aimed at boosting fuel quality, a deputy energy minister said.

Iraq is fully committed to delivering on OPEC’s Nov. 30 agreement to reduce supplies, Oil Minister Jabbar al-Luaibi said Thursday in Cairo at a meeting of the Organization of Arab Petroleum Exporting Countries, known as OAPEC.

Benchmark Brent crude oil futures LCOc1 were trading up 56 cents, or 1 percent, at $55.48 a barrel at 1329 GMT. U.S. West Texas Intermediate (WTI) crude futures CLc1 were up 29 cents at $52.41 a barrel, not far off a one-week high of $52.52.

Brent crude futures were trading at $54.02 per barrel at 0808 GMT, flat from its last settlement. U.S. West Texas Intermediate (WTI) crude was down 2 cents at $50.88 per barrel.

Japanese refiners have received notices of crude supply cuts from "some producers" for January loading, following OPEC's November 30 decision to cut production.

Iraq plans to increase crude-oil exports in January, government records show, immediately raising questions about its commitment to slashing production in line with OPEC’s landmark production agreement last month.

Operations have restarted at two key oil fields and a connected pipeline in Western Libya that have been shut down for over two years, Libyan officials said, following an agreement with local tribes.

International Brent crude futures were down 58 cents at $55.14 per barrel at 1054 GMT. U.S. West Texas Intermediate (WTI) crude oil futures were down 61 cents at $52.37 a barrel.