The United Steelworkers of America has withdrawn charges that accused Tesla of illegally firing workers at its South Buffalo plant for their pro-union stance, in an unfair labor practice charge filed in June with the National Labor Relations Board.

The union has not explained why it dropped the charges.

The Steelworkers and a second union, the International Brotherhood of Electrical Workers, launched an organizing drive last December at the solar products plant. On June 19, the Steelworkers filed its charge with the NLRB.

Documents obtained by The Buffalo News under the Freedom of Information Law revealed that the union alleged several workers were fired at the plant in retaliation for their union support. While the document was partially redacted, it appeared the allegations involved as many as six workers.

The document also said the Steelworkers union alleged that Tesla "interfered" with efforts by at least one person to secure another job, in "retaliation" for "outspoken union support."

Tesla has called the allegations "without merit."