U.S. commercial crude stocks are forecast to have climbed by 3.7 million barrels last week to extend their record build for the 14th consecutive week, according to an analysts’ poll by Reuters on Monday.

U.S. oil output from shale reserves is set to fall by 45,000 barrels per day to 4.98 million in May from April, the first monthly decline in over four years, the U.S. Energy Information Administration said on Monday.

Read MoreOPEC slams oil producers with ‘go-it-alone’ attitudes

Iran urged the formation of a new Yemeni government on Monday and offered to assist in a political transition, comments likely to anger Saudi Arabia, which is backing Yemen’s president against a rebel force allied with Iran.

Russia ended a self-imposed ban on supplying Iran with a defensive missile system on Monday, while launching an oil-for-goods barter deal with Tehran in moves suggesting Moscow could have a head-start over other nations when Iran sanctions are lifted.

U.S. Secretary of State John Kerry will urge U.S. Congress

this week that he should be given until June 30 to secure a final nuclear deal with Iran that would lift sanctions on Tehran.

Islamic State militants entered Iraq’s largest refinery in Baiji early on Monday, setting fire to three oil storage tanks, before being beaten back by security forces and coalition air strikes, local officials said.

Libya’s eastern oil port of Hariga reopened on Monday after weather conditions improved, an oil official said.