This means that the Belgian Government is no longer on speaking term with them.
However, the Syrian Ambassador cannot be forced to leave as he is also his country's ambassador to the EU.
Syria has declared the ambassadors of the United States, France, the UK, Switzerland, Turkey, Italy and Spain and the Chargés affaires of Belgium, Bulgaria, Germany and Canada “undesirable”.
None of the diplomats in question are currently on Syrian soil.
In recent months numerous ambassadors have left Syria in protest at the government’s tactics in dealing with the uprising.