GREENBELT, Md. – The father of a Marine whose funeral was picketed by anti-gay protesters from a fundamentalist Kansas church filed an invasion-of-privacy suit against the demonstrators yesterday.

It is believed to be the first lawsuit brought by a soldier’s family against Westboro Baptist Church of Topeka, Kan., whose members routinely demonstrate at military funerals around the country.

Albert Snyder of York, Pa., the father of Lance Corporal Matthew Snyder, is seeking unspecified damages. The younger Snyder, 20, died March 3 after an accident in the Al Anbar province of Iraq. He was buried in Westminster, Md.

“We think it’s a case we can win because anyone’s funeral is private,” a Snyder lawyer, Sean Summers, said. “You don’t have a right to interrupt someone’s private funeral.”

Members of Westboro say the military deaths in Iraq are God’s punishment for America’s tolerance of gays. They typically carry signs with slogans such as “God Hates Fags” and “Thank God for IEDs,” a reference to the roadside bombs used by insurgents.

The church has inspired dozens of state laws banning funeral protests, including a Maryland law that did not go into effect until after Snyder’s memorial.

A spokeswoman for the small congregation, Shirley Phelps-Roper, said it is the first time Westboro has been sued by a soldier’s family.

“We were exercising our First Amendment rights,” she said.