The oil price plummeted well below $45 a barrel today as the Opec cartel yesterday decided not to cut production.

Members had been split about how to stave off a total collapse of the oil price, which only last summer was peaking at more than $147 a barrel.

While some argued for a big cut in output to keep a floor under the price, others warned that such a move could harm the world's already recession-bound economy, triggering an all-out depression that would itself push the oil price down.

In the event, the latter camp prevailed at the Vienna summit, deciding instead to enforce better compliance with previous cuts of 4.2 million barrels a day.

Discipline is famously slack among Opec members as poorer countries always secretly sell more oil than agreed.

Generally, the cartel has only adhered to about four-fifths of previous agreed curbs.

London Brent crude fell $1.10 to $43.83, while New York crude fell $1.76 to $44.49.

"It's a very reasonable decision for Opec to take at this point, but that means they shouldn't expect to see oil prices at $50 for the foreseeable further," said Jonathan Kornafel, Asia director of US-based Hudson Capital Energy.

A survey last week showed world demand for oil contracting quicker than the industry expected, while the International Energy Agency lowered its oil demand forecast by more than a million barrels a day for 2009.