BAGHDAD — Two coordinated suicide bombings near and inside a mosque in Baghdad killed at least 13 worshipers on Tuesday, Iraqi police and an Interior Ministry source said.

The attack will amplify concerns that Iraq is being dragged towards an all-out conflict as its delicate sectarian balance comes under growing strain from the civil war in neighboring Syria.

More than 1,000 people were killed in militant attacks in Iraq in May, according to the United Nations, making it the deadliest month since the sectarian war of 2006-2007.

The first bomber detonated his charge at a checkpoint, around 100 meters away from the mosque in the Aal-Qahira district of northern Baghdad, and was followed minutes later by a second who blew himself up inside the building.

"The (second) suicide bomber detonated himself among the worshippers, who were gathering after the call to prayer," said policeman Furat Faleh, who was near the site of the blast.

The conflict in Syria, where mainly Sunni rebels are fighting to overthrow a leader backed by Iran, is inflaming sectarian passions across the region. Iraqi Sunnis and Shi'ites have crossed into Syria to fight on opposing sides.

In Iraq, both sects have been targeted in an intensifying campaign of violence since the beginning of this year, coinciding with protests by the country's minority against the government. — Reuters