Analysts point to rising diplomatic tensions over Iran as the main reason for the rise.
The oil market has been unnerved by Iran's capture last week of 15 British navy personnel, as well as the United Nations decision on March 24 to impose new sanctions against Tehran over its nuclear program.
Meanwhile, a senior Iranian military official has warned the United States against launching any attack.
The ISNA news agency quotes the naval forces commander of Iran's elite Revolutionary Guard Corps, Morteza Saffari, as saying Iranians would not allow "one American soldier" to enter their country.
(AFP, AP, Reuters)
Buses being produced at a factory in Tehran (Fars)
IN NEED OF DIVERSIFICATION. Populist Iranian President Mahmud Ahmadinejad is having trouble fulfilling his promises to put the country's petrodollars on the plates of average citizens. Inflation and unemployment remain high and the economy is dominated by the energy sector.