West Texas Intermediate futures for August delivery climbed to $61.12 (+0.18%), while Brent crude for August advanced to $64.59 (+0.22%) a barrel. Today investors are waiting for data on U.S. crude inventories (14:30 GMT), while the deadline for an agreement on Iran nuclear program will be the center of attention next week (June the 30th).

Some sources say that Iran has at least 34 tankers of oil ready to be sold as soon as sanctions are lifted. At the same time Saudi Arabia, OPEC's largest producer, is not going to reduce output to allow Iran claim its market share. This could push oil prices down. In addition to that, Gulf exporters may offer discounts to their customers to protect their own interests.

However there are still obstacles on the way to an agreement and the June 30 dead line could be postponed.