NEW YORK: - Two American-born boys, who attended a madrassa in Karachi for nearly four years, have returned to Atlanta in the U.S. State of Georgia, after a campaign for their release by a documentary filmmaker,  according to a media report. Noor and Mahboob Khan, whose parents are of Pakistani origin, are featured in a new documentary "Karachi Kids" by filmmaker Imran Raza, which is set to be released next week. The boys' father, Fazal Khan told The Atlanta Journal-Constitution, a newspaper, that he sent them to the Jamia Binoria, a prominent madrassa in Karachi, because he wanted them exposed to Islam. He said he had tried to bring his sons home but the boys couldn't get exit visas. "I sent a ticket. But I couldn't get the paperwork," he was quoted as saying in the Journal-Constitution on Wednesday. "I'm responsible for my children." Raza had been working to get the boys home when U.S. Congress Michael McCaul, a Republican from Texas, got involved. In a July 4 visit to Pakistan, he asked President Pervez Musharraf to release the Khan brothers. The boys were sent home just a few days later. Federal Bureau of Investigation spokesman Richard Kolko declined to say whether the agency is questioning the Khan brothers. He said earlier in an e-mailed statement that the FBI helped coordinate the boys' return in conjunction with the U.S. State Department. In a statement posted on the documentary's Web site on Thursday, Raza said he is grateful that Noor and Mahboob, who are 17 and 16,  are home. He said hundreds more American children remain in Pakistani madrassas - many of which are considered extremist Muslim schools that indoctrinate students with radical beliefs. "This pipeline to jihad must be closed," Raza wrote on the Web site. Raza traveled to Karachi after the July 7, 2005, terrorist attack in London that killed 52 subway and bus passengers. There he found Noor and Mahboob, who had come to the school the previous year, the report said. The documentary follows the brothers, showing how their schooling affects them. In the documentary's trailer, a young Noor talks about missing his home and family. "You don't know how badly I want to go back," he says. "If there was a plane right now, I'd just go step on it and go back to America." But after a couple of years in the madrassa, Noor says he is glad his father sent him to the school. He says he doesn't believe Muslims were responsible for the Sept. 11, 2001, attacks. "Not one Jew died that day. That is what they say," he says in the film. Ericka Pertierra, a producer for the documentary, said she's identified 200 American boys in 22 madrassas, but there are many more madrassas in Pakistan. "Noor and Mahboob are just the tip of the iceberg," she was quoted as saying.