Thousands of mourners attended funerals Monday and Iraqi authorities detained 50 suspects in connection with an explosion in the Shiite holy city of Najaf that killed at least 54 people and wounded 142.
Also on Monday, a strong explosion shook the Shiite holy city of Karbala, forcing police to cordon off the area, witnesses said. There was no immediate word on casualties.
Sunday's car bombs tore through a Najaf funeral procession and a main bus station in the nearby Shiite city of Karbala, where at least 13 people were killed and 33 were wounded.
The deadliest attacks in Iraq since July were a bloody reminder that the Shiite heartland in the south — and not just the Sunni regions of central and northern Iraq — is vulnerable to the mainly Sunni insurgents aiming to wreck the country's key elections scheduled for Jan. 30.
Meanwhile, the head of the national electoral commission appealed to security forces to safeguard election officials after three were shot to death in a brazen attack Sunday by dozens of guerrillas operating openly in the heart of Baghdad. The ambush was the latest attack to target Iraqi officials working to organize the vote.
"We send an appeal to the Iraqi government and all the people to protect our employees," Abdul Hussein Al-Hindawi said. "We have no real protection because we work everywhere in the country and have more than 6,000 employees."
Authorities in Najaf banned cars from entering the downtown area that houses the Imam Ali shrine to prevent future bombings, Gov. Adnan al-Zurufi said Monday.
"Fifty people, some of them from Najaf and others from outside, have been detained. One person detained this morning is a citizen of an Arab country. They are all being interrogated," al-Zurufi said after taking part in a funeral procession attended by thousands of residents.
Najaf's police chief said that among them were people with links to the two neighboring countries.
"The police arrested some elements who confessed that they have links with the Syrian intelligence ... and a person who confessed he had links with Iranian intelligence since 1995," al-Jazaari said.
Interim Prime Minister Ayad Allawi last week accused Syria of harboring senior officials from the ousted regime of former President Saddam Hussein, including his half brother, Sabaawi. Iraq's Defense Minister Hazem Shaalan has accused both Iran and Syria of supporting terrorism in Iraq.
Asked if Sunday's attack had targeted Grand Ayatollah Ali al-Sistani, who lives several hundred yards from the site of the blast, al-Zurufi said, "We have had information for a long time that his eminence, Ayatollah al-Sistani, is a possible target but we are taking all measures to protect him."
Al-Sistani has declared that voting in the elections is a religious duty for all Shiites.
The deadly strikes Sunday highlighted the apparent ability of the insurgents to launch attacks almost at will, despite confident assessments by U.S. military commanders that they had regained the initiative after last month's campaign against militants in Fallujah.
Shiites, who make up around 60 percent of Iraq's population, have been strong supporters of the polls, which they expect will reverse the longtime domination of Iraq by the Sunni Arab minority. The insurgency is believed to include many Sunnis who have lost prestige and privilege since Saddam's fall.
Also Monday, a roadside bomb planted near Baghdad's airport destroyed a U.S. Army Humvee, the military said. One of the soldiers was wounded.
In the town of Ramadi, west of Baghdad, insurgents attacked a U.S. patrol with rocket-propelled grenades and machine guns in the center of the city, witnesses said. It was unclear whether there were any casualties in the clash.
And U.S. troops detained 19 suspected insurgents Monday during a series of raids in the village of Siwash near Tikrit. The soldiers confiscated AK-47 assault rifles and a machine gun during the raids, the military said.
Meanwhile, in a message passed on by lawyers who visited him in his cell last week, Saddam denounced the elections as an American plot.
"President Saddam recommended to the Iraqi people to be careful of this election, which will lead to dividing the Iraqi people and their land," Ziad al-Khasawneh, who heads Saddam's legal team, said in Jordan. An Iraqi member of the team met Saddam on Thursday.
Saddam said the elections "aimed at splitting Iraq into sectarian and religious divisions and weakening the (Arab) nation," said Bushra Khalil, another member of the defense team.
The Najaf car bomb detonated in central Maidan Square, where a large crowd of people had gathered for the funeral procession of a tribal sheik — about 100 yards from where al-Zurufi and police chief Ghalib al-Jazaari were standing. They were unhurt.
"A car bomb exploded near us," al-Zurufi said. "I saw about 10 people killed." Al-Jazaari believed he and al-Zurufi were the targets of the attack.
The Karbala blast destroyed about 10 passenger minibuses and set ablaze five cars outside the crowded Bab Baghdad bus station.
It was Karbala's second bombing in a week. On Wednesday, a blast at the city's gold-domed Imam Hussein Shrine killed eight people and wounded 40 in an apparent attempt to kill a top aide to al-Sistani.
"These operations aim at driving the Shiites away from the political process and toward acts of revenge to undermine the national unity," said Jalal Eddin al-Sagheer, an official with the leading Shiite political party, the Supreme Council for the Islamic Revolution. "The whole issue has to do with elections."