The changes make it harder for voters to reject the draft constitution in next week’s referendum.
The Iraqi parliament on Sunday approved new rules specifying that a simple majority of those turning out to vote are needed to approve the draft constitution.
However it would require two-thirds of those registered to vote in at least three provinces to reject it.
The changes make it harder for Sunni Arabs in provinces where they are a dominant force to reject the constitution.
“We’ve conveyed our views and concern to the Iraqi authorities,” said Stephane Dujarric, spokesman for UN Secretary General Kofi Annan.
“Ultimately this will be a sovereign decision by the Iraqis and it’s up to the Iraqi National Assembly to decide on the appropriate electoral framework,” he added.
“That being said, it is our duty to point out when the process does not meet international standards,” Mr Dujarric added.
Earlier in Baghdad, a representative of the United Nations Assistance
Mission to Iraq (UNAMI) said: “We have raised concern and are negotiating a possible solution to reach a compromise” with the government.”
“You cannot have two different meanings in one article. It’s using interpretation to your own benefit,” he said.
In Washington, State Department spokesman Sean McCormack said what the Iraq National Assembly did was “arrive at an interpretation of the law, and that interpretation is now subject to discussion between the electoral commission on one side and the National Assembly on the other,” he said.
Mr McCormack said the National Assembly should stick to the spirit and the letter of the original article.
“In doing so, we think that, whatever the result of their discussions may be, that they should aim to broaden the political consensus,” he said.
Washington has been trying to convince the Sunni minority to participate in the constitutional referendum, despite calls to boycott it.
According to Article 61C of Iraq’s Transitional Administrative Law, a two-thirds no vote in each of any three provinces is enough to reject the draft constitution in the October 15 referendum.
The original article reads: “The general referendum will be successful and the draft constitution ratified if a majority of the voters in Iraq approve and if two-thirds of the voters in three or more governorates do not reject it.”
On Sunday, parliament changed the rules to read “voter” in the first instance and “registered voter” in the second, making it more difficult for those opposed to the draft constitution to reject it.
A number of members of Iraq’s Sunni Arab minority have already called for a “no” vote to the constitution because they believe that its federalist provisions will divide the country.
Sunni Arabs form a majority in three of Iraq’s 18 provinces, but they largely boycotted general elections earlier this year.
As Iraqi security forces braced for new attacks with the start of Ramadan, about 2,500 US soldiers launched ‘Operation River Gate’ around Haditha, Haqlaniyah and Barwana, the largest sweep in the western Al-Anbar province this year.
The US army said the offensive aims “to deny al-Qaeda in Iraq the ability to operate in the three Euphrates River Valley cities.”
“Haditha is an important crossroads for smuggling activities from the Syrian border,” the military said.
The operation follows hot on the heels of ‘Operation Iron Fist’, another sweep further up river, near the Syrian border.
At least 33 rebels have been killed in the operation since it started on Saturday, the military said, adding that five US soldiers had been killed as a result of an unspecified incident.
The latest American death brings to at least 1,931 the number of US military personnel killed in Iraq since the US-led invasion of March 2003, according to Pentagon figures.
US and Iraqi security forces also sealed off a district of Ramadi, 110 km northwest of Baghdad.
And a suicide bomber exploded a car at a checkpoint leading into Baghdad’s heavily fortified green zone, killing three Iraqis.