Baghdad, Iraq ? Iraq’s Sunni Arab vice president renewed his call for Sunni-led insurgents to quickly join the Shiite prime minister’s national reconciliation effort, while a Shiite festival that drew millions of pilgrims was held without bloodshed Saturday.

Attacks across Iraq killed at least 12 people, including two gunmen and two would-be bombers. Seven apparent victims of sectarian killings, their bodies all showing signs of torture, also were found dumped on city streets and in a river.

During a meeting with community leaders from a predominantly Sunni Arab district in Baghdad, Vice President Tariq al-Hashimi said it was not too late to stop spiraling sectarian conflict, “as the rules of the game have been changed and problems can’t be solved only by weapons.”

“This is a call for the Iraqi resistance to think … and sit around the negotiating table before it’s too late,” he told about 100 people at Islamic University in the Azamiyah neighborhood. “Differences will devastate Iraq and this division is not to our benefit.”

Prime Minister Nouri al-Maliki, who announced he will be visiting Iran on Monday for talks on security and bilateral relations, unveiled a 24-point reconciliation plan last month that he hopes will bridge the religious, ethnic and political divisions feeding Iraq’s violence.

The plan includes an offer of amnesty to members of the Sunni Arab-led insurgency not involved in terrorist activities and calls for disarming primarily Shiite sectarian militias.

Shiite pilgrims light candles to mark the birth anniversary of Shiite Imam al-Mahdi on Saturday in Karbala, Iraq. Authorities estimate that 3 million to 4 million people were in Karbala for the festival observing the 15th day of Shaaban.

But no major Sunni Arab insurgent group has publicly agreed to join the plan, and many Shiite militias are controlled by legislators themselves. Car bombings, mortar attacks and shootings have killed hundreds of Iraqis in the past few weeks.

Amid worries about sectarian attacks, including an assault by snipers that disrupted a Shiite observance in Baghdad last month, a major security operation was mounted in the Shiite holy city of Karbala, 50 miles south of Baghdad, to protect Saturday’s festival observing the birthday of Imam al-Mahdi, a ninth century religious leader.

In most Shiite Muslim sects, Mahdi is considered the last “imam,” or leader of the Shiite community. The son of the 11th imam, Hasan al-Askari, he is said to have disappeared in the ninth century. But Shiites believe he is still alive and will one day return as a savior of mankind.

Authorities imposed a four-day vehicle ban in Karbala, while thousands of Iraqi police and soldiers – backed by air support from the U.S.-led coalition – fanned out across the city to ward off potential suicide bombers.

Many pilgrims walk to Karbala from across Iraq. But while several attacks on processions heading to the city were reported in the days before the festival, the event itself passed without violence and authorities lifted the vehicle ban Saturday afternoon.

Authorities estimated that 3 million to 4 million pilgrims attended the festival.