By JEFF AMY, Associated Press

JACKSON, Miss. (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 checked employee badges of 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.

"It's pretty obvious to us and now it has been substantiated" by the NLRB, said UAW Secretary-Treasurer Gary Casteel, who leads organizing efforts.

Some workers at the 6,400-worker complex are Kelly Services employees, and the labor board charges that a Kelly supervisor named Phillip Crain made remarks on Facebook in March 2015 that amounted to threats to close the plant if workers chose a union. It has long been illegal under federal law for managers to threaten to close a plant or lay off workers for supporting a union.

"Nissan is currently building 2 plants in Mexico as we speak," Crain wrote March 22 in a screenshot provided by the UAW. "Union comes into Canton, goodbye 15-20K jobs. Keep playing, the Japanese will not play your game."

The company at the time only planned one new plant in Aguascalientes, Mexico.

Bajaj said Crain "is not a Nissan employee and had no authority to speak on the company's behalf." Crain did not immediately respond to a Facebook message from The Associated Press.

Nissan limits use of cameras to protect its trade secrets, not to impair worker rights, Bajaj said. She said Nissan checks employee badges to make sure people are present legally on Nissan property but doesn't make a record of such checks.

Nissan has until Friday to respond to the labor board. The company could chose to settle the charges or present evidence at a hearing before an administrative law judge. No hearing has been scheduled so far on the complaint.

One of the earlier allegations claims Nissan illegally stifled workers' right to wear pro-union or anti-union clothing when it created a uniform policy in 2014. The second allegation claims a Nissan manager illegally questioned and threatened pro-union workers in Canton in 2014 and 2015.

The UAW has long sought to unionize the Canton plant, but workers haven't petitioned for a vote. Union supporters have broadly aired claims that Nissan has intimidated workers. The company says its workers are free to unionize. Managers, though, have made statements opposing unionization.

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An earlier version of this story has been corrected to show that Nissan has a spokeswoman named Parul Bajaj, not a spokesman named Parul Baraj.

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