Syria has declared as unwelcome the ambassadors of several Western states; a week after governments around the world expelled its top diplomats.
The US, UK, French and Turkish envoys were among those designated "personae non gratae".
Many have already left.
President Bashar al-Assad has blamed outside powers for Syria's divisions.
Meanwhile, the UN has said the Syrian government has agreed to allow aid agencies to enter the four provinces that have seen the most violence.
Procedures would be streamlined for granting visas to staff from nine UN agencies and seven international NGOs.
The UN will open field offices in the provinces of Deraa, Deir al-Zour, Homs and Idlib.