Four days of US and British air strikes on Iraq ended over the weekend without interruption to Iraq's 1.8 million barrels per day (bpd) of crude exports.

Liftings of from the country's Gulf Port of Mina al-Bakr had proved a little slow but no shipments had been cancelled, industry officials said.

Pipeline deliveries from the Kirkuk oilfields to the Turkish Mediterranean terminal of Ceyhan on Sunday also were running to plan.

Yet good demand last week as buyers covered their requirements ahead of the Christmas holiday season means that supply is now scarce enough to stem any backward price slide.

A shortage of December cargoes in the North Sea spurred buyers to seek out cargoes in January.

Second decade January Forties cargoes traded at a hectic pace last week, partnered by Oseberg and Ekofisk trades all at good premiums for the sellers.

Inthe Mediterranean, Urals and Kirkuk prices also firmed sharply on the threat to supplies after buyers cleared out near-term Urals availabilities to cover themselves in the event of Iraqi interruptions.

Urals sellers were reluctant to show out cargoes as any halt to Kirkuk exports would send premiums hurtling higher.

"Even though Iraqi exports haven't been stopped the sellers should still get around the last number done, although they won't now get much higher," said one trader.

West African grades have already got support from the crisis, as they could have provided another alternative for Mediterranean buyers if they were deprived of Iraqi crude.

But eastern buyers are taking less January loading West African crudes than in their bumper December purchases, undermining some of the strength.

"There is definitely going to be no more West African crude going east this month than last and there will probably be a fair bit less," said one trader.

Eastward arbitrage talk has also involved more North Seacargoes, with Scandinaivan producers seeking to sell Very Large Crude Carriers of Oseberg into Taiwan.