Iraq's political rivals met to discuss a proposed new power-sharing accord on Monday but ended a first day of talks without a deal as the Sunni, Shiite and Kurdish blocs stuck to their demands.
While the leaders said talks would continue in Baghdad on Tuesday and Wednesday, twin bombings in the Shiite holy cities of Karbala and Najaf killed at least 18 people and wounded 58, mostly Iranian pilgrims.
The meeting in the northern city of Arbil attended by Prime Minister Nouri al-Maliki and his chief rival, former premier Iyad Allawi, followed an agreement on Saturday between the main Shiite bloc and a Kurdish coalition.
But their opening remarks to the three-day meeting indicated neither Maliki nor Allawi had backed down from their positions, prolonging a deadlock which has left Iraq without a government since a March 7 legislative election.
"It is necessary quickly to form a government which reflects the results of the elections," said Allawi, whose party narrowly won the polls and who accuses his rival of refusing to respect the results.
"We must be equal in rights, duties and power-sharing, without anyone having the upper hand," said Allawi, who also accuses Maliki of monopolizing power and insists on constitutional amendments to lessen the influence of the premier.
While Allawi insisted the election results be respected, Maliki in his remarks referred to respect for the constitution, which reserves maximum rights for the premier's post.
"Partnership must be concluded with true partners who respect the constitution," Maliki said.
We must be equal in rights, duties and power-sharing, without anyone having the upper hand
With the political deadlock still in place, a suicide bomber in Karbala drew his booby-trapped vehicle next to a bus carrying Iranian pilgrims, detonated his payload and killed 10 people, four of them pilgrims from Iran, police said.
A second attack targeted three buses carrying Iranian pilgrims in Najaf, another shrine city in southern Iraq, where a bomb explosion killed eight people, all but two of them from Iran.
Hundreds of thousands of Iranian religious tourists have visited Shiite holy sites in neighboring Iraq since the 2003 U.S.-led invasion toppled Sunni dictator Saddam Hussein.
Saddam crushed insurrections by Iraq's Shiite majority, banned Shiite religious festivals and fought an eight-year war with Shiite power Iran.
It is necessary quickly to form a government which reflects the results of the elections
Post of parliament speaker
Against the background of a flare-up in violence since the end of October, Iraqiya members said their Sunni-backed party was being pressed to accept the post of parliament speaker.
Iraqi Kurdistan's regional president Massud Barzani had called the meeting in the Kurdish capital of Arbil.
The Kurds -- kingmakers by virtue of their seats in parliament -- have been shrewdly trying to extract as many concessions as possible from both sides in return for their support.
The Kurdish coalition has thrown its backing behind Maliki.
But Barzani said at the end of the first day of talks that his bloc's final position on whom it backs as president, prime minister and parliament speaker will be announced after the Baghdad meetings.
"The most important issues must be decided in the next two days," Barzani told reporters.
"The three positions will be discussed tomorrow and the day after, and the decision of the Kurds will be announced in the meeting of parliament," which is scheduled for Thursday.
"Until now, Iraqiya has not told us that it would not take part in a government led by Maliki," Barzani said.
Government spokesman Ali al-Dabbagh said on Sunday a deal had been clinched the previous day between the National Alliance, which represents the main Shiite parties, and the Kurdish coalition.
"An agreement was reached ... in which Jalal Talabani (a Kurd) will continue as head of state, (Shiite) Nouri al-Maliki will stay on as prime minister and Iraqiya will choose its candidate for parliament speaker," Dabbagh told AFP.
Dabbagh said that despite outstanding issues, Iraq's parliament would meet as planned on Thursday to choose a speaker, the first step towards forming a new government.
Iraq's second general election since the 2003 U.S.-led invasion ended in deadlock after none of the main parties won enough of the 325 seats in parliament to form a majority government.
Iraqiya won the election with 91 seats, followed by Maliki's State of Law Alliance with 89.
Parliament has since remained in hiatus, but on October 24 the supreme court ordered MPs to resume work and choose a speaker. The constitution stipulates that a speaker, president and prime minister must be elected in that order.
Maliki's alliance with the Kurds gives the sitting prime minister a clear majority in parliament.