Prices were given further upward momentum by signs that Organisation of Petroleum Exporting Countries (Opec) kingpin Saudi Arabia was not initially offering major oil companies extra supplies in September as it had done this month.

London's Brent crude futures ended 98 cents stronger at $30.85 bringing gains since Monday to more than $2. US benchmark crude futures soared to end 85 cents strongerat $31.20.Dealers in London said that heavy fund buying on both sides of the Atlantic and whopping gasoline gains in New York also added fuel to the fire. Nymex gasoline ended over four cents stronger at 92.50 cents a gallon.

Oil shot higher after some oil majors said that Saudi Arabiahad cut initial September supplies compared with final August volumes, which were bolstered by extra barrels issued late in July. Major customers said they were still confident that extra Saudi barrels could be offered later."We have still got lots of time left for September," an oil executive said. "I won't be at all surprised if the Saudis allocate us extra barrels later this month."European lifters of Saudi crudes said on Thursday that their volume allocations were unchanged in September from August.

The news added to already bullish sentiment kicked off on Wednesday by American Petroleum Institute data showing US crude inventories at the lowest levels since March 1976. Oil markets have been surprised by the recent slump in US inventories despite two production hikes by the Opec this year by a total 2.4 million barrels per day (bpd) to tame runaway prices.Opec has an official output ceiling of 25.4 million bpd, supplying roughly a third of global demand of 76 million bpd.

Saudi Arabia, the world's largest crude exporter, pledged inearly July to add a further 500,000 bpd to supplies to cool overheated prices.Riyadh failed to win backing for its proposal for a third collective Opec output hike but was believed to be going it alone by discreetly leaking extra barrels to the market.

The kingdom, which was expected to raise production by 250,000 bpd in July and by the same amount in August, has been silent on its production level.But while traders are convinced that the kingdom has turnedup its taps, it remains unclear whether Saudi output has been boosted by the full amount it pledged.

A US oil source said late on Wednesday that Saudi Arabia was on track to pump the full half a million barrels of additional crude by the end of this month.

The source said that Riyadh was even prepared to supply more oil if it should prove necessary in order to lower prices.The Paris-based energy watchdog, the International Energy Agency, said on Wednesday that additional Saudi production accounted for more than one half of a 235,000 bpd increase in Opec supplies in July.It said there were indications that Saudi output was up 100-150,000 bpd, although the increase may have been twice as large but only began in the middle of the month.