In an angry response to the move by Britain, China, France, Russia and the United States in the early hours of yesterday, Iran also warned it would hit back in the region if put under severe international pressure.
It also emerged yesterday that Iran has given the International Atomic Energy Agency (IAEA) a sensitive document that appears linked to nuclear warhead designs in a show of apparent openness designed to stave off being reported to the Security Council.
Diplomats said the one and a half page document, which described how to cast fissile uranium into the hemispherical shape of warheads, was given to IAEA inspectors last week.
The agreement by the five permanent members of the Security Council to call for the IAEA to refer Iran to the full council, where it could face sanctions, was hailed by Tony Blair.
"I hope it's sending a message that the international community is united," the Prime Minister said.
But Ali Larijani, Iran's chief nuclear negotiator, responded angrily, amid signs that Russia and China are stalling over the issue.
He said: "We consider any referral or report of Iran to the Security Council as the end of diplomacy. If these countries use all their means ... to put pressure on Iran, Iran will use its capacity in the region."
It was not clear what regional capacities he meant. Analysts and diplomats say Iran, with its links to Islamist parties and militants, has the means to create trouble for the West in Iraq, Lebanon, the Palestinian territories and elsewhere.
Iran, which insists its nuclear programme is purely peaceful, said this month it was resuming nuclear research which had been suspended for two and a half years.
It removed UN seals on uranium enrichment equipment at its Natanz plant on 9 January, but there was no sign it had actually begun enrichment there.
Mr Larijania added: "In case of any referral or report to the council, we are obliged to lift all the suspensions and stop implementation of the Additional Protocol based on a law passed by parliament."
The Additional Protocol of the nuclear Non-Proliferation Treaty, signed but not ratified by Iran, gives UN inspectors greater access to suspected sites.
The nuclear warhead document showed how to cast "enriched, natural and depleted uranium metal into hemispherical forms", the diplomats said.
Iran was under increased pressure after an agreement, reached following talks that went into the early hours of Monday morning in London among the Security Council's big five, plus Germany and the European Union, that the IAEA should report to the council on what Tehran must do to co-operate with the agency.
However, with Russia and China opposed to hasty action, the agreement delayed any decision on a formal referral of Iran to the council, where it could face sanctions, until after a scheduled IAEA meeting on 6 March.
In a declaration that seemed at odds with Mr Blair's assertion of international unity on the issue, Sergei Lavrov, the Russian foreign minister, said: "The Security Council will be informed about the state of the nuclear programme, but will not pass any resolutions regarding it."
Russia is building Iran's nuclear reactor at Bushir and it is anxious to avoid any talk of UN sanctions which might cut the contract.