A union alleges that Tesla fired some workers at its Buffalo solar products plant because of their pro-union stance and that the company in at least one case tried to interfere with a worker's efforts to find another job.

A few additional details were revealed in a document released by the National Labor Relations Board in response to a Freedom of Information Law request by The Buffalo News. The NLRB is investigating the charge, which was filed June 19.

The Pittsburgh-based United Steelworkers union, one of two unions attempting to organize workers at the South Buffalo plant, filed the charge last week. The two unions launched their drive last December.

A partially redacted document released by the NLRB omits the names of the workers who allegedly were fired in retaliation for supporting the union. It appears the allegation involves as many as six workers.

The document also says the union alleges that Tesla "intentionally interfered" with efforts by at least one person to secure another job, in "retaliation" for "outspoken union support." The document does not provide further details, nor does it identify how many workers were the target of the alleged interference in seeking another job.