At several rail depots across Belgium rail staff took industrial action on Monday, following four cases of violence against guards that occurred during the weekend.
One of the guards who was attacked is still receiving hospital treatment for his injuries.
The guards say that they are sick of aggressive behaviour by passengers.
On Friday, Brussels airport was shut for a few hours after security staff and fire fighters downed tools in a row about working conditions.
About 200 flights were cancelled on Friday, affecting some 26,000 passengers.
