Oil prices have declined as doubts over OPEC’s capacity to curb crude supplies strengthen, completely negating the gains received from the reports of a drop in US oil inventories.

Benchmark Brent crude slipped by 27 cents to reach $51.87 a barrel, while the US West Texas Intermediate (WTI) crude fell by 21 cents to $48.96 per barrel, reported Reuters.

The American Petroleum Institute (API) reported that crude stockpiles in the US dropped by 7.8 million barrels last week to 478.4 million due to an increase in refining activity.

API also noted that petrol inventories increased unexpectedly.

Sumitomo Global Research president Bob Takai was quoted by the news agency as saying: “Oil is stuck in a range of $45-$50 for WTI and a bit more for Brent for now.”

"Oil is stuck in a range of $45-$50 for WTI and a bit more for Brent for now."

OPEC members and other participants of the oil curb deal are struggling to maintain compliance level as oil production resumed in Libya, with a consistently higher output from Nigeria.

OPEC member countries and other key oil producers agreed to reduce production by 1.8 million barrels per day by March next year.

After a meeting in Abu Dhabi, officials from a joint OPEC and non-OPEC technical committee called for a higher adherence to the pact among participating countries.

Saudi state oil company Aramco previously announced it would decrease crude allocations next month to its worldwide customers.