Police are searching for a man who escaped from Safi detention centre last night, the Home Affairs Ministry said in a statement.
The ministry did not say how the detainee got away, although it said that a number of security guards at the detention centre would be disciplined as a result.
Magistrate Antonio Micallef Trigona is leading an inquiry into the escape.
Safi detention centre made headlines two weeks ago after the Home Affairs ministry announced that it had rounded up a number of failed asylum seekers and sent them there pending "further steps". The detainees, who are all believed to be from Mali, are likely to be deported.