Oil prices rose slightly on Thursday, as investors looked to an output cut deal to be extended between the Organization of Petroleum Exporting Countries (OPEC) and its allies during an upcoming meeting next week, Trend reports citing Xinhua.

The two sides will discuss their oil policies at the meeting scheduled for July 1-2 in Vienna, and decide whether to extend the six-month-long agreement on cutting production, which they inked last December to slash 1.2 million barrels per day.

Iraq's Oil Minister Thamer Ghadhban said Thursday that the two sides are expected to roll over their previous deal and calls for "even more" curbs have emerged.

"The rollover at least would be at the same level because it has not been very effective, it has been effective to a certain level to minimize the glut in the market, but there are now ideas or calls for agreeing (on) even more," Ghadhban was quoted as saying by Reuters during a conference in London.

The West Texas Intermediate for August delivery increased 0.05 U.S. dollar to settle at 59.43 dollars a barrel on the New York Mercantile Exchange, while Brent crude for August delivery rose 0.06 dollar to close at 66.55 dollars a barrel on the London ICE Futures Exchange.