International benchmark Brent crude increased to $71.73 a barrel at 1217 GMT while American benchmark West Texas Intermediate (WTI) was $64.62, according to official figures on Friday.
The price of Brent crude oil opened above $70.61 per barrel at 0540 GMT at trading start on Monday while WTI registered at $63.35 per barrel at the same time, sustaining five-month highs as global oil supply tightens with the Organization of Petroleum Exporting Countries' (OPEC) and Russia led non-OPEC countries' cuts, along with sanctions on Iran and Venezuela.
Crude prices have been on the rise since the beginning of 2019 with falling global oil supply.
Due to U.S. sanctions on Iran and Venezuela, both countries' oil production levels are in decline, and are expected to account for a total of 1.76 million barrels per day (bpd) in lost output this year.
The supply cut deal of Saudi Arabia-led OPEC and Russia led non-OPEC continues to put an upward pressure on crude prices.
In addition, in Libya, tensions between the UN-backed Government of National Accord and east Libya-based commander Khalifa Haftar escalated, posing risks against the secure supply of crude from the OPEC nation.
-OPEC and IEA released monthly oil reports
Global oil supply has decreased in March 2019 by 0.14 million barrels per day (mb/d) month on month (m-o-m) to average 99.26 mb/d, OPEC showed on Wednesday.
OPEC's monthly oil market report said that for March 2019, OPEC crude oil production decreased by 534,000 b/d to average 30.02 mb/d, according to secondary sources.
However, non-OPEC supply, including OPEC natural gas liquids (NGLs), increased by 0.39 mb/d m-o-m to average 69.24 mb/d, up by 2.67 mb/d on an annual basis.
According to OPEC's report, the share of OPEC crude oil in total global production declined by 0.5% m-o-m to 30.2% in March 2019.
Data from the International Energy Agency (IEA) on Thursday showed that global oil supply dropped by 340,000 b/d in March to 99.2 mb/d, as OPEC and non-OPEC cuts deepened and Venezuelan output fell sharply.
OPEC's largest producer Saudi Arabia saw its output drop to its lowest in over two years, boosting compliance to153% with these supply cuts, according to the IEA's Oil Market Report.
In March, OPEC crude oil production tumbled by 550,000 b/d.
On the demand side, the Organization for Economic Cooperation and Development (OECD) countries saw their consumption decline at the beginning of last year due to the weak economy in Europe, the IEA said.
By Gulsen Cagatay