JACKSON (AP) — Federal labor regulators have added to charges to a complaint that Nissan Motor Co. and a contract worker agency at Nissan’s Mississippi plant have violated workers’ rights.

The National Labor Relations Board, in a March 31 filing, claims a Kelly Services supervisor illegally threatened the plant would close if the United Auto Workers union begins representing workers. The new charges also claim security guards improperly harassed union supporters, and that a Nissan policy banning unauthorized photos and recordings is illegal.

Those new claims were added to two previous allegations that the labor board made in a 2015 complaint.

Nissan spokeswoman Parul Bajaj repeated an earlier statement that said “filing charges with the NLRB is a common tactic in an organizing campaign.”

But in this case, while the United Auto Workers made the charges that spurred federal action, the board’s complaint signaled government investigators believe the allegations are true.