Reuters reports: More than 1,000 people were killed in violence in Iraq in May, making it the deadliest month since the sectarian slaughter of 2006-07, the United Nations said on Saturday, as fears mounted of a return to civil war.

Nearly 2,000 people have been killed in the last two months as al Qaeda and Sunni Islamist insurgents, invigorated by the Sunni-led revolt in Syria and by Sunni discontent at home, seek to revive the kind of all-out inter-communal conflict that killed tens of thousands five years ago.

“That is a sad record,” Martin Kobler, the U.N. envoy in Baghdad, said in a statement. “Iraqi political leaders must act immediately to stop this intolerable bloodshed.”

The renewed bloodletting reflects worsening tensions between Iraq’s Shi’ite-led government and the Sunni minority, seething with resentment at their treatment since Saddam Hussein was overthrown by the U.S.-led invasion of 2003 and later hanged.