Cabin Services Norway, which took over the company's Norwegian cabin staff in March, sent out a text message to all staff on Friday, according to Tønsberg Blad newspaper.
The message informed them that the system of "ID-tickets", on which cabin staff previously only had to pay tax, had been terminated with immediate effect.
"This is a consequence of the employees going on strike," Norwegian's head of information Lasse Sandakerveien-Nielsen told the paper. "We have to take action and it is not uncommon to do this when there is a conflict. This is something that Parat and The Cabin Crew Association knew would come if there was conflict."
The punishment makes good a message the airline sent out by text message on Tuesday night, warning employees they would lose free tickets, be forced to relocate to Oslo, and, in the case of Danish employees, be transferred to an employment agency, thereby losing much of their job security.
Parat, the Norwegian union coordinating the strike action, on Thursday afternoon accused the airline of "brutalisation" of its staff, in a release.
"We don’t want to see brutalisation such as we are witnessing here in either the Norwegian or the European labour market," Turid Svendsen, the union's chief negotiator, said in a press statement on Thursday afternoon.
"We believe that this type of intimidation by the company is in violation of agreements signed between the company and the union, because this is regarded as an action aimed at avoiding a strike and affecting the outcome of a conflict of interest."
Parat said it was coordinating with the European Transport Workers' Federation, which brings together unions from across 41 European countries and the ITF, which has five million members inn 150 countries, to try and prevent Norwegian bringing in temporary staff from other countries to replace striking workers.
"The airline has announced measures to maintain flights in the case of a strike, and Parat regards this action as blacklegging," it wrote in its statement.
It also warned that the airline was in danger of causing a major strike which could affect flights across Europe.
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"The Norwegian airline with the same name is in danger of being thrown into a comprehensive strike by its cabin crew in Norway and Denmark within a short period of time," Parat warned.
"The airline...is accused of treating its employees with little respect, while attempting to crush the union that currently organises most of its employees in Scandinavia."
At present just one member of Norwegian's staff, René Gustavsen, is on strike, but a further 1,300 staff are expected to join him within the next 18 days.