Crude oil rocketed to a record high of almost $140 a barrel on Monday despite news that Saudi Arabia was ready to raise output.

Diesel use in South Africa, driven by home generators and the trucking of coal to Eskom power stations

Opec secretary general Abdullah al-Badri on Tuesday appealed for calm, saying the record-high oil price was unbearable and did not reflect any shortage of supply.

High global oil prices and cuts in fuel subsidies in some countries will slow growth of oil demand this year, the International Energy Agency (IEA) forecast on Tuesday, also reporting a surge in supply in May.

Concerns were growing on Monday night over a summer of coordinated European fuel protests after tens of thousands of Spanish truckers blocked roads and the French border, sparking similar action in Portugal and France.

Oil prices dropped more than $1 on Monday after rocketing to record heights near $140 per barrel late last week, but some analysts warned of a bubble that could burst soon.

World crude prices are expected to reach $150 per barrel by the end of summer, Iran's representative to the Organisation of the Petroleum Exporting Countries (Opec) was quoted as saying on Sunday.

Group of Eight energy ministers on Sunday looked inward for solutions to oil's unrelenting rally.

United States Energy Secretary Sam Bodman called on Saturday for more countries to scrap fuel price subsidies that stoke oil demand.