Oil prices traded higher on speculation on the higher oil demand as a tropical storm Bill headed towards the oil-producing state of Texas. More than 45% of U.S. oil refining capacity is located along the Gulf Coast.

Investors are awaiting the release of the U.S. oil inventories data. The American Petroleum Institute (API) is scheduled to release its U.S. oil inventories data today, and U.S. oil inventories data from the U.S. Energy Information Administration is expected on Wednesday.

The debt talks between Greece and its creditors remained in focus. Greek Finance Minister Yanis Varoufakis said that Athens will not provide a new reform proposal.

German newspaper Süddeutsche Zeitung reported that capital controls could be imposed this week. Athens denied this report.

Investors are also awaiting the release of the Fed's monetary policy meeting results. The results are scheduled to be released tomorrow. Analysts expect that the central bank will keep unchanged its monetary policy.

WTI crude oil for July delivery increased to $59.88 a barrel on the New York Mercantile Exchange.

Brent crude oil for July rose to $63.97 a barrel on ICE Futures Europe.