Mayors are not allowed to block the deportation of failed refugees and illegal immigrants, according to two professors in their advice to three ministers.

The case arose when Giessenlanden mayor Els Boot clashed with immigration minister Gerd Leers earlier this year after the minister ordered the deportation of an illegal Afghan man.
The man, who is suspected of war crimes, was refused leave to stay despite being the only carer for his sick wife and their children, all of whom are in the Netherlands legally.
Boot ordered local police not to cooperate with the deportation.
Advice
Leers, justice minister Ivo Opstelten and home affairs minister Liesbeth Spies turned to the two professors for advice.
They say police are under the exclusive orders of the immigration minister when carrying out deportations. Mayors cannot call on the public service role of the police or on a fear for civil disorder to block deportations.
The ministers have written to parliament to say they will be following this advice.