Oil prices rose slightly on Monday as investors' long-time oversupply concerns were eased by a decline in U.S. oil rig count.

In the week ending Aug. 9, U.S. oil rig count dropped six to 764, marking the lowest level since February 2018, U.S. energy services firm Baker Hughes said in its weekly report on Friday.

The reading was also 105 lower than the 869 of the same week last year.

However, the market remained worried that worsening global trade prospects could lead to further global economic slowdown, and reduce demand for crude oil.

The West Texas Intermediate (WTI) for September delivery added 0.43 U.S. dollar to settle at 54.93 dollars a barrel on the New York Mercantile Exchange, while Brent crude for October delivery rose 0.04 dollar to close at 58.57 dollars a barrel on the London ICE Futures Exchange.