Unidentified gunmen killed at least 40 Syrian soldiers and government employees who were being taken to the Syrian border by Iraqi authorities on Monday after fleeing into Iraq from a Syrian rebel attack last week, Iraqi officials said.
A convoy carrying the Syrians was ambushed in Iraq's western province of Anbar, where thousands of Iraqi Sunnis have been protesting daily for more than two months against the Shi'ite-led government and the perceived marginalisation of their sect.
The conflict in neighbouring Syria, where mainly Sunni Muslim rebels are fighting to overthrow a leader backed by Shi'ite Iran, is whipping up sectarian tensions in Iraq and the wider Middle East.
That has raised concerns of a return to the kind of sectarian strife that killed tens of thousands in Iraq in 2006-2007.
"The incident took place in Akashat when the convoy carrying the Syrian soldiers and employees was on its way to the al-Waleed border crossing," a senior Iraqi official told Reuters.
"Gunmen set up an ambush and killed 40 of them, plus some Iraqi soldiers who were protecting the convoy."
The Iraqi officials said some 65 Syrian soldiers and government employees had handed themselves over to Iraq on Friday after anti-government rebels seized the Syrian side of the Yaarabiya frontier crossing.
Anbar's Sunnis have been venting frustrations that have built up since the U.S.-led invasion overthrew the Sunni Muslim dictator Saddam Hussein and empowered Iraqi's majority Shi'ites.