Baghdad, Iraq ? Iraq’s interim prime minister warned Monday that insurgents are trying to foment sectarian civil war as well as derail elections, while thousands of mourners turned out for funerals in the Shiite holy cities of Najaf and Karbala a day after car bombs killed 67 people.

Prime Minister Ayad Allawi said the mainly Sunni Muslim insurgents, blamed for Sunday’s bloody attacks, want to “create ethnic and religious tensions, problems and conflicts … to destroy the unity of this country.”

“These attacks are designed to stop the political process from taking place in Iraq,” Allawi told reporters. He added that his administration would not be deterred despite expecting more strikes before key Jan. 30 parliamentary elections — the first free vote in Iraq since the overthrow of the monarchy in 1958.

In a new attack Monday in Karbala, a bomb exploded at a police checkpoint, but inflicted no casualties. Police said they arrested the attacker.

Shiite Muslims, who make up around 60 percent of Iraq’s people, have been strong supporters of the electoral process, which they expect to reverse the longtime domination of Iraq’s Sunni minority. The insurgency is believed to draw most of its support from Sunnis, who provided much of Saddam Hussein’s former Baath Party leadership.

Shiite officials and clerics blamed Sunnis for Sunday’s bombings, which caused the worst carnage in Iraq since July. The strikes appeared designed to cause heavy casualties, and provoke reprisals by Shiites against Sunnis.

Allawi said Monday that a big factor in the strength of the insurgency was the dismantling of Iraq’s security forces after the U.S.-led invasion that ousted Saddam’s regime.

“What is happening is that we are facing an enemy heavily supported even in some cases with superior weapons,” he said. “We will have setbacks, we are having setbacks, but we are determined to continue the fight.”

There have been fears the intimidation campaign aimed at electoral workers will not only hurt preparations for the ballot, but also could reduce voter turnout enough to bring the legitimacy of the election into question.

People look at buildings destroyed in Sunday's car bomb blast in the Shiite holy city of Najaf, Iraq. More than 65 people were killed in bomb blasts Sunday in Najaf and Karbala. Iraq's interim prime minister warned Monday that insurgents may be targeting Iraq's largest segment of the population in hopes of fomenting civil war.