Tesla Inc on Wednesday laid off dozens of employees from its Autopilot department at its Buffalo plant in New York, a day after workers launched a campaign to form a union, according to a complaint filed with a government agency.

Earlier this week, Tesla workers in New York said they will unionize with Workers United Upstate New York, which would help give them a voice at their workplace.

The Workers United Upstate New York union in a filing with the U.S. National Labor Relations Board (NLRB) on Wednesday accused the world's most valuable automaker of hitting back by terminating some of the employees "in retaliation for union activity".

The company fired more than 30 employees, the union said in the statement, adding that the workers also received an email with an updated policy, which prohibits them from recording workplace meetings without all participants' permission.

"This policy violates federal labor law and also flouts New York's one-party consent law to record conversations."

The employees had asked the electric carmaker to respect their right to organize a union and called on the company to sign the Fair Election Principles, which would prevent Tesla from threatening or retaliating against the workers.

Chief Executive Elon Musk has in the past been vocal about his opposition to unions and said in a 2018 tweet that employees would lose their stock options if they formed a union, prompting the NLRB to ask him to delete the tweet.