Brent crude futures climbed 36 cents, or 0.7%, to $51.22 a barrel, as of 0151 GMT, and U.S. West Texas Intermediate (WTI) crude futures added 34 cents, or 0.7%, to $47.96 a barrel.
Crude rose along with gains in Asian shares, with Japanese
Forecasts for tightening U.S. crude oil stocks also added support to prices.
U.S. crude oil stockpiles are expected to have declined last week, while refined products inventories likely rose, a preliminary Reuters poll ahead of this week's data showed on Monday.
Five analysts polled by Reuters estimated, on average, that crude stocks likely fell by 2.1 million barrels in the week to December 25.
Still, concerns over coronavirus lockdowns are capping gains.
A new variant of the virus in the United Kingdom has led to the reimposition of movement restrictions, hitting near-term demand, and weighing on prices. In contrast, hospitalizations and infections have surged in parts of Europe and Africa.
A January 4 meeting of the Organization of the Petroleum Exporting Countries (OPEC) and allies including Russia, a group known as OPEC+, also looms over the market.
OPEC+ is tapering record oil output cuts made this year to support the market. The group is set to boost output by 500,000 barrels per day (bpd) in January, and Russia supports another increase of the same amount in February.
Russian Deputy Prime Minister Alexander Novak said Monday he expected there would be 5 million to 6 million bpd additional oil demand in 2021, which has not fully recovered from the pandemic.
Money managers raised their net-long U.S. crude futures and options positions in the week to December 21, the U.S. Commodity Futures Trading Commission said on Monday. The speculator group raised its combined futures and options position in New York and London by 4,455 contracts to 325,787 during the period.