The U.S. Treasury Department said Thursday it was taking joint action with Turkey against a network it said played a key role in money management, transfer and distribution for the Islamic State group operating in Iraq and Syria.

Turkey has frozen the assets of members to the network, who also were added to the U.S. sanctions list, the Treasury Department said in a statement.

Those sanctioned included an Iraqi national living illegally in Turkey, Brukan al-Khatuni, his two sons, and two businesses they used to transfer money on behalf оf the Islamic State between Turkey, Iraq and Syria, it said.