Updated

A New Jersey veteran was denied entry at Six Flags Great Adventure due to an “offensive” T-shirt he wore in support of the U.S. Marines.

Mario Alejandro, 33, of Woodbridge, said he was stopped while entering the theme park in Jackson on Saturday. The father of three, who took part in the initial invasion of Iraq in 2003 as a member of the Marines, said the T-shirt — emblazoned with the words “Keep Calm and Return Fire” above a red, white and blue machine gun — caught the eye of a security guard at the front gate.

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“I can’t let you into the park with that shirt on. That shirt’s offensive,” Alejandro recalled the guard saying to NJ.com. “I said it’s not offensive, it’s a military shirt. I told him that I am an Iraq veteran … I served in the war. But he said: ‘I don’t care, you have to take it off … or you need to buy another shirt to put over it.”

Alejandro, who could not be reached for comment Friday, refused to remove the T-shirt from The Reconnaissance Foundation, a nonprofit group supporting Marines and their relatives, or to buy another garment, leading the security guard to call a supervisor.

“I saw him talk to two women in white shirts, who looked at me and then shook their heads,” he told NJ.com. “And then the man grabbed my arm and asked me to leave. I told them that it’s not offensive, that it’s a military shirt and that it means nothing. But they said: ‘I don’t care, get out of the park.’”

A spokeswoman for Six Flags Great Adventure told FoxNews.com that the theme park stands by the decision.

"We do not allow guests to wear T-shirts with images of machine guns in our parks," spokeswoman Kristin Siebeneicher said via e-mail." We apologize for any inconvenience we caused this guest, however we stand by our policy, which does not permit clothing with vulgar, offensive or violent language or images. Our goal is to maintain a fun, safe and family-friendly environment."

Siebeneicher noted Six Flags' "longstanding relationship" with U.S. veterans and the park's special discounts and events to honor the nation's veterans and their relatives.

Alejandro, meanwhile, said no veteran deserves the same treatment he encountered last week.

“I fought for this country,” he said. “I laid in a hole for 36 hours with no sleep, and had friends die for this country and so the people here could have the freedom to [do] things like visit amusement parks. So when they told me that I couldn’t come in there with my family because of my shirt — a patriotic shirt — it hurt a lot. No other veteran should ever have to experience that.”

FoxNews.com's Joshua Rhett Miller contributed to this report.