In a draft statement expected to be approved at a summit in Brussels, they urged Iran to comply without delay with resolutions by the United Nations Security Council and the U.N.'s International Atomic Energy Agency. The statement said the council of 27 EU states "expresses its grave concern that Iran has so far done nothing to rebuild confidence of the international community in the exclusively peaceful nature of its nuclear programme".
While reiterating that the EU remained open to a negotiated solution, the statement added:
"Iran's persistent failure to meets its international obligations and Iran's apparent lack on interest in pursuing negotiations require a clear response, including through appropriate measures."
The term "appropriate measures" is used by the EU to refer to sanctions. The statement said the bloc would support steps by the U.N. Security Council and also stood ready to take its own measures.
The EU leaders said EU foreign ministers would consider options at their next meeting in Brussels on Jan. 21.
Britain, France and the United States warned Iran on Thursday that it may face new sanctions over its nuclear programme, but the other permanent members of the U.N. Security Council, Russia and China, hinted that they were not convinced more punitive steps were needed.
The French U.N. Ambassador Gerard Araud told the U.N. Security Council Paris was ready to begin drafting a sanctions resolution soon.
U.N. diplomats have said senior officials from the United States, Britain, France, Germany, Russia and China — the six powers spearheading efforts to persuade Iran to halt enrichment — might meet as early as next week to discuss Iran, which the West suspects is pursuing nuclear weapons.
Iran rejects the allegations, along with U.N. demands that it suspend a programme it says is intended solely for the peaceful generation of electricity.
The EU statement also reiterated deep concern about human rights violations in Iran and increasing concerns about the situation of staff members of EU missions and EU citizens who have been put on trial in Iran.
It repeated EU policy that "any action against one EU member state is considered an action against the entire EU".
(Reporting by David Brunnstrom; Editing by Noah Barkin)
