Crude oil prices rose by more than 2% at the beginning of the week's trading, supported by news that President Trump may be discharged from hospital as soon as today, less than a week after his positive COVID-19 test.
This eased political uncertainty in the markets, pushing Brent crude prices to $40 a barrel, while US crude reached $38 a barrel.
Oil also received support from growing strike action in Norway that led to the shutdown of four Equinor oil and gas fields. The strike could reduce the country's production capacity by up to 330k barrels, or 8% of its total production, according to the Norwegian Oil and Gas Association.
Prices had fallen by more than 4% on Friday amid uncertainty about President Trump's health, adding to concerns about the global economic recovery.
On the other hand, OPEC member Libya last week increased production nearly three-fold to 270k barrels per day last week after eastern forces eased a blockade on the country's oil infrastructure.
Meanwhile, recent price increases have prompted some US producers to resume drilling, with data from Baker Hughes showing on Friday that US energy companies had added oil and natural gas rigs for the third consecutive week - the first time this has happened since October 2018.