The National Labor Relations Board has filed a complaint against Tesla (TSLA) - Get Report , claiming the electric automaker constrained and interfered with employee's union activities at its Fremont, Calif. facility.

The complaint, filed Thursday, mentions several occurrences in which Tesla tried to interfere with and hinder its employees from establishing a union. Among the allegations against Tesla from employees included forcing them to work long hours for inadequate pay, and maintaining a hazardous work environment.

The complaints were brought on behalf of three workers with the United Auto Workers union, which in the past has urged Tesla employees to establish a union.

Tesla has denied the charges against it. "These allegations, which have been filed by the same contingent of union organizers who have been so outspoken with media, are entirely without merit," Tesla said.

Shares of Tesla were rising in Friday morning trading.

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