Workers at four Swedish ports blocked the loading and unloading of Tesla cars Tuesday in a growing strike movement over the US company's refusal to sign a collective wage agreement with mechanics.On Tuesday, the Swedish Transport Workers' union began a "sympathy measure" to support IF Metall by blocking the "loading and unloading of Tesla cars" at four Swedish ports in the cities Malmo, Sodertalje, Gothenburg, and Trelleborg.