Oil prices neared $146 US a barrel Thursday for the first time ever on reports of declining U.S. stockpiles and the threat of conflict with Iran.

Comments by Saudi Arabia's oil minister suggesting his country had no immediate plans to boost production also lifted prices.

The price for light, sweet crude for August delivery hit a record intraday high of $145.85 a barrel on the New York Mercantile Exchange. It later finished at $145.29, up $1.72 from Wednesday, for a third consecutive record settlement price.

The latest spike means a barrel of crude has gone up by more than 50 per cent since the end of last year, when oil was going for $96 a barrel.

The push above $145 a barrel was seen as a last technical barrier to prices hitting $150, in what analyst Olivier Jakob of Petromatrix in Switzerland called "the Morgan Stanley self-fulfilling prophecy."

In early June, a prediction by Morgan Stanley analyst Ole Slorer that oil prices could reach $150 by the July 4 weekend caused the Nymex contract to jump nearly $11 in a single day.

Speaking Thursday in Madrid, Saudi Arabia's oil minister, Ali Naimi, left the door open for increased output, but said the kingdom's oil customers were satisfied and that no production growth was planned for now.

Mixed picture of energy use

The U.S. Energy Department's Energy Information Administration said Wednesday crude oil supplies fell by two million barrels last week, or about 800,000 barrels more than analysts surveyed by the energy research firm Platts had predicted.

However, the report offered a mixed picture of energy use by the world's thirstiest oil consumer. Gasoline supplies unexpectedly grew by a considerable amount, and demand continued to slide, suggesting record fuel prices are prompting a shift in American driving habits.

Ongoing rhetoric about possible attacks on Iran, the world's fourth-largest oil producer and OPEC's second-largest exporter, also left the market jittery.

Traders are worried Tehran could try to halt shipments and seize control of the strategically important Strait of Hormuz if attacked by Israel or the United States. About 40 per cent of the world's tanker traffic passes through the Middle Eastern choke point.

Iran's foreign minister did not rule out the possibility that Iran could try to restrict oil traffic in the strait if the country is attacked.

A senior U.S. military commander vowed to ensure that the strait remains open.

"We will not allow Iran to close it," said Vice-Admiral Kevin Cosgriff, commander of the 5th Fleet based in Bahrain, after talks with naval commanders of Persian Gulf countries in the United Arab Emirates.

The sabre-rattling has left energy traders on edge as they try to ascertain the likelihood of a Middle East flare-up and the effect it could have on the world's already tight supply of oil.