Oil prices rose today, helped by expectations that an OPEC-led output cut would be extended beyond June but gains were pegged back by concerns about persistently high crude inventories.
The Organisation of the Petroleum Exporting Countries and some non-OPEC producers agreed to curb production from January 1 by 1.8 million barrels per day (bpd) for six months to drain crude from record stockpiles.
But oil inventories remain stubbornly large.
OPEC sources have indicated the group's members increasingly favour an extension but want the backing of non-OPEC oil producers, which have yet to deliver fully on existing reductions.
Brent crude, the international benchmark for oil, was up 36 cents at $51.98 per barrel, rebounding from last week's three-month low of $50.25 but well below January's surge above $58 in the wake of the output cuts.
US West Texas Intermediate crude rose 31 cents to $48.53.
Further gains may depend on data on US inventories from the American Petroleum Institute (API) later tonight.
Last week's report by the API industry group showed a surprise fall in overall stockpiles in the week to March 10. This time analysts expect a rise back towards record highs.
Stockpiles at the Cushing, Oklahoma delivery hub for WTI may be a particular focus in the API data.
Stocks at Cushing rose in the week to March 10, helping to widen the premium for Brent over WTI. The gap now stands at around $2.70 for May delivery.
However, if supply restraints stay in place, analysts said solid global demand could gradually help rebalance the market, even with expanding US production of shale oil.