A federal lawsuit has been filed on behalf of a group of Christian high school students in New York who said their principal banned them from starting a Christian club.

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"The principal said, 'I don't want any of these Christian clubs at my school,'" said David Cortman, an attorney with the Alliance Defense Fund, a conservative advocacy legal group.  The ADF filed the lawsuit Monday against the Hicksville Union Free School District in Central Islip, NY.

"Public schools cannot ban Christian student clubs simply because they are religious," Cortman said. "If officials at government-run schools did their homework, they'd know that students have a constitutionally protected right to express their beliefs."

Last October, students at Hicksville High School requested official recognition for the Frontline Club. They had a dozen classmates willing to join the club and had secured a faculty advisor. However, the principal denied their request - and said she did not want a Christian club in her school.

An assistant to the school district's superintendent told Fox News Radio they were unaware of the lawsuit and said talking to the superintendent was "not an option."

Cortman said in 2008 the principal denied a similar request and said that any religious club must be "multi-faith," open to all religions and must allow non-believers to lead the club.

As for the Frontline Club, Cortman said parents received a letter from the school explaining the club ban was due to financial issues.

"She stated that they didn't have money in the budget for a Christian club," he said. "But they allowed a ping pong club, a ski club, a debate club and in fact, they are funding 35 clubs."

"It's ridiculous that Hicksville High School says it has no budget for a Christian club but somehow has enough for a ping pong club.