AFP - Pressure mounted on Sunday as Iraqi leaders prepared to meet to try to end a deadlock over a stalled election law amid growing concerns that the country's January polls will have to be delayed.

Prime Minister Nuri al-Maliki warned that postponing the elections would threaten the legitimacy of parliament and the government, while a top Iraqi general cautioned that a delay risked increasing instability.

As if to confirm Lieutenant General Ali Ghaidan Majeed's warning, twin suicide car bombs in central Baghdad on Sunday morning killed at least 64 people and wounded more than 600.

The remarks followed calls for a breakthrough from US President Barack Obama and the special UN envoy to Iraq, while the US ambassador to the United Nations held talks with the leader of the country's semi-autonomous Kurdish region, whose MPs' views have been one of the stumbling blocks.

An Iraqi MP, meanwhile, predicted the meeting of the national security political committee, an advisory body of senior Iraqi politicians including Maliki, will fail to reach agreement and that the nationwide ballot will be postponed by one or two months.

"If it is postponed from the current date, the government will lose its legitimacy and parliament will lose its legitimacy," Maliki said in a speech on Saturday.

"We will go back to square one and we will return to sectarianism... Therefore, our voices must unite to hold the election on its present date."

The meeting of the national security political committee was scheduled for 3:30 pm (1230 GMT), days after the Baghdad parliament gave up attempts to agree a new law to govern the general election, scheduled for January 16.

If it reaches a deal on Sunday, parliament will meet again on Monday to ratify the new law.

The deadlock threatens the poll as the electoral law is supposed to be in place 90 days before voting takes place. Constitutionally, the election must be held by January 31.

"What we are afraid of, if there is any delay to the elections... is this may create problems for security in general," Majeed, commander of Iraqi ground forces, told AFP in an interview.

However, he said Iraqi security forces have a "Plan B" that they can implement if the election is postponed.

Majeed warned that insurgents could also step up attacks in the months ahead of, and following, the election, which proved prescient as twin attacks struck government buildings in central Baghdad at around 10:30 am (0730 GMT) on Sunday.

His fears echoed those of a representative of Iraq's top Shiite cleric Grand Ayatollah Ali al-Sistani, who warned at Friday prayers of unease among senior Shiite clergy about the failure to adopt an election law.

"A delay in the elections will create a constitutional and political void and upheaval in security," Sheikh Abdul Mahdi al-Karbalai said.

At issue are proposed changes to the law that would require parties to publish full lists of their candidates rather than simply the name of their electoral list.

Another major hurdle has been the lack of agreement the fate of the oil-rich province of Kirkuk, which the Kurds have long demanded be incorporated in their autonomous region in the north despite the opposition of its Arab and Turkmen communities.

In Arbil, meanwhile, Susan Rice, Washington's envoy to the UN, held talks on Saturday with Kurdish President Massud Barzani about the elections and other issues, a government official said.

Her visit followed Obama's remarks earlier this month, during Maliki's visit to the White House, calling for an election law to be agreed as quickly as possible.

The parliamentary impasse has triggered US concern that its troops may have to stay on in numbers into next year.

Michele Flournoy, US undersecretary of defence for policy, told lawmakers in Washington on Wednesday that failure to resolve the issue within the next week or so "might well have implications" for the American military drawdown.

As part of a Baghdad-Washington security agreement, US combat troops must leave Iraq by the end of August and all American forces must withdraw by the end of 2011.

UN special envoy Ad Melkert warned Iraqi MPs the delay in setting the ground rules for the general election -- only the third since the US-led invasion of 2003 -- threatens to undermine "the credibility of the electoral process."