Iran oil production dropped by 40%: US

"In just a year, Iran's oil production has dropped some 40 per cent, from 2.5 million barrels per day in 2011 to 1.5 million barrels as of this June," the State Department spokesperson Victoria Nuland said.

"So that is the equivalent of about USD 9 billion in lost revenue per quarter. So this work that the international community is doing to pressure Iran is having an effect, and we need to keep it up," Nuland said, adding that this statistics was based on its own information, open source and other sources.

The United Sates, she said, is concerned that Iran has a nuclear programme and that it has failed to demonstrate that it is only for peaceful purposes. "And as we've said, the onus is on Iran to come clean with the international community and

demonstrate to us that there is no military programme," she said.

"One of the reasons that the sanction regime has been effective, that we believe Iran's come back to the table, is because the international community has been so unified in its demands, and we're looking for that same kind of unity out of

the BOG meeting that's ongoing now," the US official added.