Unrest, Asian growth and speculation explain $100 oil: analysts

Oil prices have quadrupled in five years, propelled by geopolitical tensions, surging demand from Asia and new buying interest from investment funds, analysts say.

The weakening US dollar, which fell again on the foreign exchange market on Wednesday, is also to blame because it makes oil cheaper for buyers using stronger currencies.

Some analysts had expected geopolitics to fade in importance in 2008 after a fall in tension between key oil exporter Iran and the United States, which had been threatening military action over the Islamic republic's disputed nuclear programme.