The premium for ICE Brent for December over January traded around 60 cents per barrel, while the spread between December 2011 and December 2012 was below $2.20 both at or below their lowest levels for three months.

"Many of the very large plays, the funds, are already out of the front month," said Christopher Bellew of oil brokers Jefferies Bache in London. "There is no sign of a scramble to cover positions."

In recent months, the expiry of the front-month Brent futures contract has led to a series of spikes in the spreads between prompt and later months as traders have been forced to cover positions before the front contracts cease trading.

The spread between Brent's first and sixth-month forward contracts hit a record high of almost $7 last month head of the expiry of November ICE Brent.

The European spot market for light, sweet crude oil has been kept tight by the loss of more than 1.5 million barrels per day (bpd) of Libyan crude during the uprising and overthrow of former dictator Muammar Gaddafi and by some disruption to exports from West Africa.

But Libyan crude oil supplies have started to return to the market over the last few weeks and the country, which has the largest oil reserves in Africa, now expects to produce more than 800,000 bpd by the end of this year and at least 1.3 million bpd in a year, not far below its pre-conflict output of 1.6 million bpd.

"The prompt crude market is not that tight any more," said a crude oil trader with a large bank. "This expiry is the quietest we've seen for a while."

In another sign of improving prompt oil supplies in Europe, the swaps market for North Sea crude has eased back over the last month with front CFD (contract for differences) spread against January Brent dipping to around 50 cents.

The front CFD spread hit a high of around $3.80 in mid-September just before the expiry of October Brent.