Bombs targeting Sunnis, including two near a mosque and one at a funeral procession, killed 51 people in Iraq on Friday, officials said, after dozens died in two days of attacks on Shiites. The violence raises the spectre of tit-for-tat killings common during the height of sectarian bloodletting in Iraq that killed tens of thousands of people, and comes at a time of simmering tension between the country's Sunni minority and Shiite majority.

Three car bombs exploded south of Baghdad on Monday, killing nine people and wounding 70 others, police said, the latest attacks in a seven-day wave of violence that has left more than 230 people dead across Iraq. In the deadliest attack on Monday, two car bombs exploded in Amara in south Iraq, killing seven people and wounding 45, a senior police officer and a doctor said. A third car bomb exploded in Diwaniyah, also south of Baghdad, killing two people and wounding 25, police Brigadier General Abduljalil al-Assadi and a doctor said.

The United Nations warned on Friday that Iraq is at a "crossroads" and appealed for restraint, as a bloody four-day wave of violence, including multiple attacks at mosques, killed 195 people. "I call on the conscience of all religious and political leaders not to let anger win over peace, and to use their wisdom, because the country is at a crossroads," UN envoy Martin Kobler said in a statement. The call came a day after Prime Minister Nuri al-Maliki warned of a return to "sectarian civil war."

Bombs exploded at four Sunni mosques in and around Baghdad on Friday, killing four people and wounding 50, an interior ministry official and medics said. The bombers struck after the main weekly prayers as four days of violence that have killed more than 190 people raised fears of a return to all-out sectarian conflict. A bomb exploded inside Al-Kubaisi mosque in south Baghdad, killing four people and wounding 36, while bombs near Al-Shaheed Yusif and Malik al-Ashtar mosques in the north of the capital wounded at least 11, the official and medics said.