Fred Phelps and his daughter Shirley Phelps-Roper, who belong to the Westboro Baptist Church in Kansas, were planning to come to Britain to protest outside a performance of "The Laramie Project," the Times of London reported Friday.
The plan recounts the death of gay college student Matthew Shepard who was killed in Laramie, Wyo., in 1998. The play is to be performed Saturday at Queen Mary's College.
Phelps, 79, and his daughter, 51, are known for protesting at American soldiers' funerals, where they display banners with phrases such as "God Hates Fags." Members of the church say they believe U.S. troop deaths in Iraq and Afghanistan are punishment for America's tolerance of gays.
Phelps and his daughter have been labeled as "extremists" by the British government.
"The Home Secretary has excluded both Fred Phelps and his daughter Shirley Phelps-Roper from the U.K.," a Border Agency spokesman said. "Both these individuals have engaged in unacceptable behavior by inciting hatred against a number of communities."
Peter Tatchell of the gay rights group OutRage! said he disagreed with the decision to ban the Phelpses.
"The Phelpses are odious, homophobic bigots. They give Christianity a bad name," Tatchell said. "Objectionable though they are, I don't agree with them being banned."