He added that the new measures are not designed "to punish the Iranian population, but to bring them [the Iranian government] back to the negotiating table."

Earlier on during his UN speech, he also accused Iran of helping the Syrian government to butcher civilians.

"It is clear that we have all the proof we need that Iran is intervening by human and material means in Syria, and this is unacceptable," Hollande noted.

French foreign minister Laurent Fabius told Reuters in the margins of the UN event that the new sanctions will be "on the financial and trade side."

Back in Brussels, the French press agency AFP cited an anonymous EU diplomat as saying the UK wants to see a "full freeze on Iran's central bank, on all its financial transactions" and "a wide sectoral ban on shipping."

AFP's contacts added that "most member states are largely supportive" of the plan, but that France itself, Germany, Spain and Sweden want to stop short of a full-blown trade embargo on the Middle East power.

The previous round of EU sanctions, imposed on 1 July, included an oil ban and forbade transactions with the Iranian central bank. But the bank ban allowed EU countries to do business with it if it relates to trade in other areas, such as food or textiles.

For its part, Iran believes it has shown good faith by resuming international talks on the nuclear issue earlier this year.

It also says the UN's Vienna-based non-proliferation watchdog, the IAEA, has not put forward any evidence that its nuclear enrichment work is aimed at making weapons.

EU contacts previously told EUobserver that the international talks, which are chaired by EU foreign policy chief Catherine Ashton, have begun addressing some key issues, such as the closure of one enrichment facility in Fordow. But they added that Iran is wasting time on debating the format of the talks themselves. "They are masters of obfuscation," one source said.

US President Barack Obama in his UN address also on Tuesday noted that the Iranian programme could lead to war.

He said that "a nuclear armed Iran is not a challenge that can be contained" and that the US would "do what it must" to stop it from getting the bomb.

The EU sanctions decision is due on 15 October.