Foreign Secretary Jack Straw yesterday hailed Iraq's constitutional referendum as "very good news for all Iraqis".

Overall turnout in the vote, which passed off relatively peacefully, was more than 60 per cent of the 15.5 million voters. Initial forecasts of the result may come today.

Mr Straw said "the whole process took place in remarkable calm given the overall security situation in Iraq.

"What this referendum shows is the hunger of Iraqis to exercise the same democratic rights the the rest of us, and to defy the terrorists.

"Whatever the result, it is a major step on the way to establishing a democratic, and we hope, peaceful Iraq."

The constitution looked likely to secure approval, despite strong opposition from Sunni Arabs who turned out in high numbers in an effort to stop it. The constitution is popular among the Shi'ites, who make up 60 per cent of the country's 27 million people, and the Kurds - another 20 per cent

The apparent victory was muted, though, by the prospect that the vote result might divide the country further.

US Secretary of State Condoleezza Rice, in London for talks, predicted the constitution was likely to pass, although she cautioned that she did not know the outcome for certain.

The constitution is a crucial step in Iraq's transition to democracy after two decades of rule by Saddam Hussein's dictatorship.

Washington is hoping it passes so that Iraqis can form a legitimate government, tame the insurgency and enable the 150,000 US troops to begin to withdraw.

Later, Mr Straw underlined suspicions that Iran had a hand in bomb attacks on British troops in Iraq.

Last week, Prime Minister Tony Blair said there was evidence the attacks in southern Iraq led back to Iran.

His remarks followed the disclosure by a senior UK official that the sophisticated bombs that killed eight British soldiers were supplied by the Hezbollah terror movement via the Iranian Revolutionary Guard.

Yesterday, Mr Straw said: "What we have presented to the Iranians is evidence which, in our judgment, clearly links the improvised explosive devices which have been used against British and other troops, mainly in the south of Iraq, to Hezbollah and to Iran.

Secretary of State Rice backed up the British position, saying: "I have every reason to believe that the British are right about this.

"I trust the British on this issue."