Crude exports from Iran appear to have fallen this month by around 300,000 barrels per day (bpd), or 14 percent, according to estimates from industry consultant Petrologistics and a large European oil company.
It is the first sizable drop in oil shipments from the OPEC producer since the European Union announced in January plans to embargo Iran's crude from July and Washington and Brussels sanctioned Iran's central bank.
Oil prices rose on the news, with Brent jumping more $2.45 to $125.59 a barrel.
"This is fundamentally very bullish," said Mike Wittner, head of commodities research at Societe Generale in the United States. "I think Iranian exports are going to go down much more, as the sanctions bite. It's a logical reaction for the market to go up on this."
European buyers of Iranian crude including France's Total have already stopped buying the oil, which is subject to European Union sanctions from July 1. Royal Dutch Shell is scaling back.
"We are taking less and less — very few barrels," said an official with a European oil company, until earlier this year one of the larger EU buyers of Iranian crude.
According to Petrologistics, a Geneva-based oil industry consultant, Iranian exports may amount to 1.9 million bpd in March, down from about 2.2 million bpd in February.
A source at an oil company, which still deals in Iranian crude, said the evidence pointed to an overall drop in shipments in March, seeing a decline of at least 300,000 bpd mainly because European customers are taking less.
Petrologistics is one of a number of companies which estimates oil output by tracking tanker shipments, because Iran, like many big oil exporters, does not routinely disclose how much it is supplying on a timely basis.
Iran's oil exports are difficult to track and, like those of other countries, they can fluctuate week by week. With a week to go in March, it is possible the picture may change.
"We are struggling to get the numbers nailed down," said an industry official.
Oil prices have climbed to just $20 short of their all-time high of 2008, as the tighter Western sanctions on Iran threaten to choke off its exports.
An Iranian oil official, asked on Friday to comment on whether exports had fallen, referred to remarks earlier in March by Iranian Oil Minister Rostam Qasemi who said shipments were unchanged from last year.
