"The recent rally in oil prices might have taken some by surprise as the underlying fundamental picture does not justify Brent being close to $70/bbl. This view is based on the simple fact that non-OPEC oil supply growth will trump the increase in global oil demand this year," PVM Oil Associates analyst Tamas Varga said.
"The price strength of the last couple of weeks is down to two factors. The first one is a stable OPEC output level which leads to impressive compliance (with an oil supply-cutting deal). The second one is supply-side geopolitical developments in Venezuela, Libya and Iran, the most acute of which is Iran."
The United States has threatened to withdraw from a nuclear deal that Iran signed with six nations in 2015 by a deadline it has set in May, raising the chance that it may impose sanctions on Tehran and hinder oil exports.
The Organization of the Petroleum Exporting Countries together with a group of non-OPEC producers led by Russia, has curtailed production since January 2017 to prop up prices.
The deal is scheduled to last through 2018, and there has been recent support by OPEC's de-facto leader Saudi Arabia to extend the cuts into 2019.
"Crude also received support from OPEC members as Saudi Arabia and Russia both reiterated goals to extend the production cut agreement," said James Mick, managing director and energy portfolio manager with asset management firm Tortoise.