Oil prices dropped early on Monday under pressure from a rise in oil drilling activity in the United States as energy services firm Baker Hughes said on Friday that U.S. energy companies added seven oil rigs drilling for new production in the week to April 13, bringing the total to 815 - the highest since March 2015.
Brent crude oil futures were at $71.87 per barrel at 0124 GMT, down 71 cents, or 1 percent from their previous close.
U.S. West Texas Intermediate (WTI) crude futures were down 59 cents, or 0.9 percent, at $66.80 a barrel.
Tensions in the Middle East over the weekend weighed on international stock markets early on Monday.
MSCI's broadest index of Asia-Pacific shares outside Japan slipped 0.4 percent as Chinese blue chips took an early 0.7 percent dip.
