Meanwhile, Iran has faced sanctions due to its reluctance to end a controversial nuclear programme. The country has been locked in talks with six world powers - Britain, China, France, Russia, the US and Germany - to reach an understanding, with an interim deal to lift a ban on sales to the EU and limiting them to Asia agreed in November. However, since then talks have stalled, causing Iran's petroleum exports to halve in the past two years, according to OPEC.