Iran acknowledged for the first time on Wednesday that its oil exports have fallen sharply, down 20-30 percent from normal volumes of 2.2 million barrels daily.
A National Iranian Oil Company official in Moscow denied exports had been hit by sanctions against Iran's nuclear program, saying that oilfields were under maintenance and crude production was being diverted for refining.
But the admission that exports have fallen substantially is a change of tack from Tehran which until now has denied that the U.S. and European measures have had much or any impact.
"It was 20 to 30 percent we reduce regarding to our export," NIOC official Mohammad Ali Emadi said in English. "Some part of the reduction is shifting for the refinery internally."
Customers in Europe and Asia have been scaling back purchases of Iranian crude ahead of European Union bans on imports and tanker insurance for ships carrying Iranian crude that are due to come into effect on July 1.
Emadi said Iran's normal crude exports were 2.2 million bpd, in line with external estimates. A 20-30 percent fall would put Iranian exports at 1.54-1.76 million bpd, off 440-660,000 bpd.
That is still above most third-party estimates which put Iran's crude exports in June at about 1.3 million bpd.
"We gradually started to reduce, It is not because of the sanctions but sometime regarding overhaul maintenance of the wells," said Emadi.
The NIOC official said Iran wanted to export more gas to India and Pakistan to make up for the fall in crude exports. Iran has long aspired to export gas east but would require heavy investment in a pipeline or liquefied natural gas facilities to do so.