Crude oil prices finished the week ending Oct. 2 below $40 after news that US President Donald Trump and his wife tested positive for the coronavirus.
International benchmark Brent crude was trading at $39.25 at 1245 GMT on Friday, posting a 6.6% decrease from Monday when it traded at $42.05 per barrel at 0625 GMT.
American benchmark West Texas Intermediate (WTI) traded at $37.14 at the same time on Friday relative to $42.92 a barrel on Monday.
Oil prices decreased on Friday morning over US President Donald Trump's announcement early Friday that he and first lady Melania Trump had tested positive for COVID-19 after a test of one of his closest aides was confirmed positive.
More than 207,800 people in the US have died from the disease so far, with over 7.27 million people infected, according to the latest data from Johns Hopkins University.
Trump's positive test results announcement continued to pressure prices on Friday afternoon, causing concerns over market volatility ahead of the Nov. 3 election.
Oil was already under pressure due to uncertainties over the restart of stalled talks between US Republicans and Democrats on the stimulus package for the coronavirus pandemic.
Democrats unveiled a new $2.2 trillion economic stimulus plan last week, and House Speaker Nancy Pelosi and Treasury Secretary Steven Mnuchin started renegotiations this week.
Pelosi said late Thursday she had not yet reached an agreement with Mnuchin, but the House of Representatives approved the bill in a 214-207 vote.
Mounting concerns expressed by the Organization of the Petroleum Exporting Countries (OPEC) over rising oil output and lower demand put downward pressures on prices, and fears over a COVID-19 resurgence also prompted concern over falling demand.
The market is due to receive more oil after Libya's National Oil Corp (NOC) lifted a force majeure on the country's oil ports and facilities last month, following the lifting of the eight-month oil export blockade by eastern Libyan commander Khalifa Haftar.
By Ebru Sengul Cevrioglu