The Asian Football Confederation (AFC) have ruled that matches between clubs from Saudi Arabia and Iran must be played at neutral venues.
The AFC's competition committee had given both football federations until March 15 to resolve an impasse created by Saudi government restrictions prohibiting any nationals traveling to Iran. It agreed to delay matches between Saudi and Iranian clubs until later in the AFC Champions League.
The AFC issued a statement on Wednesday saying that diplomatic relations had not improved, and it had given both federations until March 25 to submit proposals for neutral venues.
Saudi and Iranian clubs are scheduled to meet in groups A, B and C of the continental championship in April and early May.
Al-Ittihad, which won back-to-back titles in 2004 and '05, are winless from three games and is set to play Iran's Sepahan in Group A on April 20 and May 4.
Also on those dates, joint Group B leaders Al-Nassr and Zob Ahan are scheduled to meet.
Another two-time Asian champion from Saudi Arabia, Al Hilal, is expected to face Group C-leading Tractor Sazi of Iran on April 19 and May 3.