Singapore — Oil prices fell on Monday, giving up earlier gains, squeezed by plentiful supply and US firms in particular increasing exports in competition with traditional producers from the Middle East in key markets like Asia.

International Brent crude oil futures were at $66.88 a barrel at 4.49am GMT, down 24c, or 0.4%, from their last close. They ended Friday little changed after touching their highest since November 16 at $67.73 a barrel.

US West Texas Intermediate (WTI) crude futures were at $57.11 a barrel, down 15c, or 0.3%, from their last settlement. WTI futures climbed 0.5% on Friday, having marked their highest since November 16 at $57.81 a barrel.

Traders said the dips were a result of ample oil supply amid surging exports from the US, forcing other producers especially in the Middle East to start offering their crude at discounts.

Under pressure from a surge in US supply, Abu Dhabi’s flagship Murban crude has sold at a discount in Asia to its official selling price (OSP) for four consecutive months — the longest stretch in nearly two years.

Cargoes bought for loading in the first four months of 2019 were sold at discounts ranging from 5c to 40c a barrel, even as producer Abu Dhabi National Oil Company (Adnoc) cut the grade’s benchmark price for four consecutive months.

US crude oil production has hit a record 12-million barrels a day, an increase of more than 2-million barrels a day since early 2018. Exports hit a record 3.6-million barrels a day in February.

The surge in US oil output counters efforts led by the Middle East-dominated Opec to cut output in order to tighten the market and prop up prices.

The Opec-led cuts as well as US sanctions against Iran’s and Venezuela’s oil exports pushed oil prices to 2019 highs last week.