Crude oil prices fell below the critical $100 a barrel level on Tuesday for the first time since April as hurricane Ike shifted its course away from the Gulf of Mexico and traders bet Opec would leave production unchanged.

Since jumping to an all-time high of $147.27 last July, the combination of the slowdown in the global economy, which is damping oil demand, and higher production from the Opec oil cartel have brought down oil prices 30 per cent.