Britain, France and Germany urged their European Union partners "to further step up the pressure" on Iran by agreeing new sanctions to undermine its nuclear drive, in a joint letter seen by AFP on Monday.
Foreign ministers of the three nations called on their EU counterparts to quickly agree punitive action in the areas of energy, finance, trade and transportation, with sanctions set to be formally adopted October 15.
The ministers said they believed previous EU sanctions had "had an enormous effect" -- notably a damaging oil embargo that came into force on July 1 -- particularly in helping bring Iran back to the negotiating table.
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"But further encouragement to Iran to engage substantively with the E3+3 is needed urgently," they wrote, referring to talks between Tehran and six world powers -- the EU three, plus the United States, Russia and China.
"We must let Iran know that we have not exhausted our options. There is also a real need for us to confirm and demonstrate our determination to partners in the region.
"We are therefore united in our belief that it is now time for the EU to further step up the pressure in order to influence the calculations of the Iranian regime," the letter said.
Saying they had together identified energy, finance, trade and transport as areas "of special importance to the Iranian nuclear programme and to its financing by the Iranian regime," they called on EU states to immediately submit proposals with a view to adopting sanctions at ministerial talks on October 15.