Iranian oil production fell 9 per cent in the first four months of this year, as new sanctions targeted the country's oil exports, according to data issued by the Organization of the Petroleum Exporting Countries (OPEC) on Thursday, dpa reported.
However, OPEC member countries have increased their overall output in recent months, reaching 31.6 million barrels per day (bpd) in April.
Iran pumped 3.2 million bpd last month, down 134,000 bpd from March.
In January, the European Union approved an embargo against Iranian oil and a freeze on the accounts of the Iranian central bank in an attempt to force Tehran to suspend uranium enrichment and shed light on alleged nuclear weapons projects.
An estimated 18 per cent of Iranian oil exports go to the EU.
India, Turkey and Japan have also cut down imports at varying degrees, as the United States increased its pressure on major customer countries.
Tehran has demanded that sanctions should be lifted as the result of upcoming nuclear talks with the US, Britain, France, Germany, Russia and China in Baghdad later this month.