The National Labor Relations Board said in a complaint filed Thursday that it is investigating Tesla (TSLA) for unfair labor practices.
Workers and the United Auto Workers Union filed complaints with the federal agency in April that make an array of allegations, including that employees at its factory in Fremont, Calif. were interrogated over union activities. They claimed management tried to prevent them from discussing these along with worker safety concerns.
The NLRB has consolidated these into one complaint and has opened an investigation.
For more on Tesla, see Fortune’s video:
An effort has been underway for years to unionize Tesla’s Fremont factory. The United Auto Workers has been working with employees since at least last year.
In response, Tesla said in a statement that the UAW has strayed from its original mission, used “every tool in its playbook” in its campaign against the company. Tesla’s complete statement is posted below.
“As we approach Labor Day weekend, there’s a certain irony in just how far the UAW has strayed from the original mission of the American labor movement, which once advocated so nobly for the rights of workers and is the reason we recognize this important holiday.
Faced with declining membership, an overwhelming loss at a Nissan plant earlier this month, corruption charges that were recently leveled against union leaders who misused UAW funds, and failure to gain traction with our employees, it’s no surprise the union is feeling pressured to continue its publicity campaign against Tesla.
For seven years, the UAW has used every tool in its playbook: misleading and outright false communications, unsolicited and unwelcomed visits to the homes of our employees, attempts to discredit Tesla publicly in the media, and now another tactic that has been used in every union campaign since the beginning of time–baseless ULP filings that are meant only to generate headlines. These allegations, which have been filed by the same contingent of union organizers who have been so outspoken with media, are entirely without merit. We will obviously be responding as part of the NLRB process.”