France, Britain and Germany have expressed "serious doubts" about Iran's intentions to revive a nuclear deal.
Earlier this month, Tehran sent its latest response to the EU's proposed text to restore the 2015 agreement under which Tehran had curtailed its nuclear programme in exchange for relief from US, EU and UN economic sanctions.
Diplomats have said Iran's response to the EU co-ordinator, seeking to link a revival of the deal with the closure of investigations by the International Atomic Energy Agency into uranium traces at three undeclared sites, was a step backwards.
The three European parties to the Joint Comprehensive Plan of Action, as the deal is formally known, vented their frustration about the issue on Saturday.
This comes as IAEA's board of governors prepares to meet on Monday, three months after the European parties adopted a resolution urging Iran to provide credible answers on the issue.
"This latest demand raises serious doubts as to Iran's intentions and commitment to a successful outcome on the JCPOA," the three countries, known as the E3, said in a statement.
"Iran's position contradicts its legally binding obligations and jeopardises prospects of restoring the JCPOA."
