The industrial action could impact between 25,000 and 27,000 air passengers.
Airport workers are walking out in protest of the 'Grinch-style behaviour’ of low-paying employers.
The European Union says that a merger between the two airlines will not breach antitrust rules.
EU antitrust officials are worried the takeover of the former Alitalia fleet could raise prices and cut choice on flights to central Europe and the US.