Labor organizers in Los Angeles have accused the Marciano Art Foundation, a private museum, of violating federal law by dismissing dozens of employees after they announced that they wanted to form a union.

In a charge filed on Thursday with the National Labor Relations Board, the organizers wrote that the foundation “has illegally discriminated against its employees by laying off employees en masse and/or closing its facility.”

The charge, filed by District Council 36 of the American Federation of State, County and Municipal Employees, asked that the foundation be required to reinstate the employees, recognize and bargain with the union and reopen the museum, which was closed this week.

A spokesman for the foundation did not immediately respond to a request for comment.

The dispute between the union and the foundation began on Nov. 1 when District Council 36 filed a petition with the N.L.R.B. seeking to represent about 70 visitor services associates and other employees at the foundation, which has a heralded collection created by Paul and Maurice Marciano, two brothers who helped build the Guess jeans empire.