The price of brent crude has risen to $111(£71.46) a barrel after the violence within Egypt. The fear is not over a fall in oil production, as Egypt is not a major producer of oil, but the possiblity of violence spreading into nearby major oil-exporting nations or to the distruption to the Suez Canal, a major supply route.
The price was driven higher in the previous session following a drop in US oil inventories and related worries over supply from the Middle East and North Africa.
The Egyptian health ministry has said at least 464 people have died and over 3,500 injured in the fighting. The Muslim Brotherhood – supporters of deposed president Mohamed Morsi – have called for further marches in Cairo to protest about the deaths.
The interim government has declared a state of emergency and a curfew from 19:00 to 06:00.