SWEDEN’S largest trade union, the white-collar and services union Unionen, has joined the dispute between the IF Metall union and e-vehicle manufacturer Tesla.

As the strike by Tesla’s mechanics in Sweden, who maintain the firm’s imported vehicles, moves into its sixth month, boss Elon Musk declared the dispute as being “over” now that the maintenance of vehicles was being carried out by 25 “temporary” staff from outside of Sweden.

But Unionen began a blockade this week affecting all work for Tesla at Dekra Industrial AB, which conducts equipment inspections.

Martin Wastfeldt, head of negotiations at Unionen, said the dispute was “fundamentally important to protect our collective agreement system.” 

Unionen said that if Tesla seeks to circumvent their blockade by hiring other providers, the union was prepared to escalate the dispute.

Unionen recently signed a collective agreement with financial tech company Klarna who had told its employees that collective bargaining did not fit with its current business model.

But when its 6,000-strong workforce threatened to strike, Klarna signed a collective agreement with Unionen.

Unionen’s involvement has also encouraged a number of Swedish employment law experts to suggest that Tesla should consider using a third party company to manage its Swedish business with a collective agreement.