Turkey is outraged over a purported pact between US-backed forces in Syria that may have allowed hundreds of Islamic State fighters to leave the city of Raqqa, with Prime Minister Binali Yildirim warning that Turkish citizens and others are now in danger of attacks by the jihadis.

The BBC reported this week that the Kurdish-led Syrian Democratic Forces (SDF) negotiated a secret deal to let hundreds of IS fighters leave their former capital last month, with the apparent blessing of US and British coalition members. Local truck drivers were hired to evacuate the fighters and their families, who have now spread through Syria, with some even crossing the border into Turkey, according to the BBC.

“These Daesh members who left there, freed with their weapons, will be the cause of the murder of who knows how many innocent people primarily in Turkey and in Europe, America and all around the word,” Yildirim told his party in parliament on Tuesday, using the Arabic term for the Islamic State.

Turkey has long warned the United States against cooperating with the Kurdish People’s Protection Units (YPG), which dominates the SDF, over its links with the militant Kurdistan Workers Party (PKK), inscribed on US, European Union and Turkish terror lists for its three-decade insurgency in Turkey that has killed 40,000 people, mainly Kurds.