Oil prices hovered close to 2019 highs on Thursday, bolstered by OPEC-led supply cuts and U.S. sanctions on Venezuela and Iran, but were prevented from rising further by slowing growth in the global economy.

U.S. West Texas Intermediate (WTI) crude oil futures were at $57.39 per barrel at 0742 GMT, 23 cents, or 0.4 percent, above their last settlement, and close to their 2019 high of $57.55 reached the previous day.

International Brent crude futures were at $67.20 per barrel, 12 cents, or 0.2 percent above their last close and not far off their 2019 peak, hit the day before, of $67.38 per barrel.

Analysts said that a global economic slowdown was preventing prices from surging beyond highs reached this week.

“Slowing economic growth will invariably lead to weakness in fuel consumption thus eroding bullish gains for oil prices,” said Benjamin Lu of brokerage Phillip Futures in Singapore.

Despite the slowdown in economic growth that emerged in late 2018, oil prices have been driven up this year by supply cuts led by the Organization of the Petroleum Exporting Countries (OPEC).

OPEC, as well as some non-affiliated producers such as Russia, agreed late last year to cut output by 1.2 million barrels per day (bpd) to prevent a large supply overhang from growing.

A presidential spokesman for OPEC member Nigeria said in a statement on Wednesday that the country was willing to limit output “so that prices (for oil) would go up.” Nigeria is part of the supply pact but its output actually climbed in January.

Another price driver has been U.S. sanctions against oil exporters Iran and Venezuela.

“Although there is no lack of resources, there is an increasing lack of access to them,” Britain’s Barclays bank said of the sanctions on Wednesday.

The main factor keeping oil prices from rising even further is soaring U.S. oil production, which rose by more than 2 million bpd last year, to a record 11.9 million bpd.

The swelling output has resulted in rising U.S. oil inventories.

U.S. crude oil stocks rose by 1.3 million barrels in the week to Feb. 15 to 448.5 million, according to a weekly report by the American Petroleum Institute on Wednesday.

Official oil inventory and production data is due to be published by the U.S. Energy Information Administration (EIA) after 1800 GMT on Thursday.