Workers at Tesla's (TSLA) - Get Tesla Inc Report final assembly plant have reached out to the United Auto Workers in an attempt to unionize the facility, according to a blog post written by a man claiming to be an employee at the facility.

Jose Moran, who identifies himself as a worker at the Fremont, Calif.-based facility, in a Medium post describes working more than 40 hours per week, including "excessive mandatory overtime," and says "preventable injuries happen often."

He said that in recent months six of eight people on his team were on medical leave at the same time due to work-related injuries, adding that "many of us have been talking about unionizing, and have reached out to the United Auto Workers for support."

Moran could not be reached for further comment. Tesla in a statement to the San Francisco Chronicle responding to the post said: "the safety and job satisfaction of our employees ... has always been extremely important to us." The company called the letter part of an effort to unionize the plant.

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"As California's largest manufacturing employer and a company that has created thousands of quality jobs here in the Bay Area, this is not the first time we have been the target of a professional union organizing effort such as this," the company said.

Moran also criticized pay rates at the factory and said that Tesla "recently" required every employee to sign a confidentiality policy that restricts workers from speaking about wages and working conditions. He stated that five members of the California State Assembly have written to Tesla calling for that policy to be retracted.

The Tesla plant, the only final assembly facility owned by a domestic automaker in the U.S. that is not unionized, has had union representation in the past. Before Tesla's ownership, the plant was home to New United Motor Manufacturing Inc., a joint venture between General Motors (GM) - Get General Motors Company (GM) Report and Toyota (TM) - Get Toyota Motor Corp. Sponsored ADR Report , and represented by the UAW.

Last year, Automotive News reported that UAW officials had had contact with employees at the Tesla plant.

The potential organizing effort comes at a time when Tesla is planning dramatically to ramp up production at the Fremont facility. The company, which delivered 76,230 vehicles in 2016, has set a goal of 500,000 deliveries in 2018.

Tesla said Thursday it intends to temporarily halt production at the facility to prepare for production of its highly-anticipated Model 3 sedan, a vehicle that is vital to the company's long-term future.