Oil prices have topped $78 a barrel today following a weak dollar and escalating tensions between Iran and the western countries, which triggered speculation over a possible supply risk encouraging investors to push prices higher.

Crude oil for January delivery increased by 91¢ to $78.38 a barrel, while London Brent crude increased by $1 to $78.20 a barrel by 6.21 GMT, according to Reuters.

The December contract, which expired on 20 November, stood at $76.72 a barrel.

In 2009, oil prices have increased by 75% because of slow global economic recovery and the weak dollar, even though the prices are still 47% less than $147 a barrel recorded last year in July.