Oil prices fell on Monday as the Greek debt crisis helped boost the dollar, making fuel more expensive to holders of other currencies, and as United Nations talks offered a chance for peace in Yemen where crude exporter Saudi Arabia is involved in a civil war.
Warplanes from a Saudi-led coalition bombarded Yemen's capital Sanaa overnight, a Reuters witness said, as warring factions prepared for talks due to start in Geneva on Monday.
Read More Fracking: On its way to the UK?
Investors are increasingly concerned about surplus supply in the global oil market with the Organization of the Petroleum Exporting Countries pumping around 2 million barrels per day (bpd) more than needed, according to most industry estimates.
Production has been increasing in top OPEC exporters Saudi Arabia and Iraq, and a deal with Iran over its nuclear program may soon lift sanctions on the Islamic Republic, allowing it to increase oil exports.