Oil prices climbed more than $1 to above $73 a barrel yesterday after major exporter Iran hinted it might use oil as a weapon in its nuclear dispute with the West.
The country's Supreme Leader, Ayatollah Ali Khamenei, warned that flows from the Gulf, which supplies nearly 20 per cent of the world's energy, would be endangered if Washington made a "wrong move" over Iran.
Officials from the world's fourth biggest oil exporter previously have said Iran would not halt crude shipments over its nuclear standoff with the West.
But comments from Khamenei, who has the final say in matters of state, suggested Tehran could disrupt supplies if pushed.
US crude traded $1.17 higher at $73.49 a barrel. London Brent rose $1.33 to $72.36.
"The threat, whilst remote, would be serious in the context of global oil markets operating with little more than two million barrels per day of spare capacity," a Citigroup report said.
Tension between Iran and the West over Tehran's nuclear programme has helped drive oil's 20 per cent rally this year.
US Secretary of State Condoleezza Rice reacted to Khamenei's comments by counselling a wait-and-see approach. Washington has offered to join European countries in talks with Iran about its atomic work, but said Tehran must first suspend uranium enrichment.
Iran so far has rejected the demand, saying enrichment was a national right.
Soaring oil prices will mean losses of $ 3 billion (£1.59 billion) for global airlines this year, industry lobby group IATA said, raising its forecast from $2.2 billion (£1.17 billion) as fuel woes outpace cost-cutting efforts.
The figure for now remains below the loss of $3.2 billion (£1.7 billion) for 2005, but IATA chief executive Giovanni Bisignani told the group's annual meeting in Paris that uncertainty remained.
"Oil is the wild card. Prices are racing ahead of efficiency gains and robbing our profitability," he said in a speech on the industry.
"The industry fuel bill will top $112 billion (£59.5 billion) this year - $ 21 billion (£11.1 billion) more than 2005," said the International Air Transport Association, which represents 261 airlines handling 94 per cent of the world's scheduled air traffic.
Fuel is expected to make up 26 per cent of airlines' average costs in 2006 compared with 22 per cent the previous year.
In order to make money, airlines need on average to fill 63.3 per cent of their available capacity by weight in 2006, but are only expected to manage 62.4 per cent, IATA said.