SANTA ANA, Calif. (Agencies) - The revelation that the FBI planted a spy in a Southern California mosque was explosive news in a Muslim community that has long suspected the government of even broader surveillance, according to a report carried by The Washington Times. Muslim-American organisations have demanded an inquiry. Some say the news has rattled their faith in American democracy. Despite the reaction, former FBI agents and federal prosecutors say spying on mosques is still one of the government's best weapons to thwart hardline elements and that the benefit to national security is likely to far outweigh any embarrassment to the agency. "What matters to the FBI is preventing a massive attack that might be planned by some people ... using the mosque ... as a shield because they believe they're safe there," said Robert Blitzer, the FBI's former counterterrorism chief. "That is what the American people want the FBI to do," he said. "They don't want some type of attack happening on US soil because the FBI didn't act on information." One of the most-heralded US terrorism convictions, for example, grew out of the work of an informant who spent months inside a New Jersey mosque and derailed a plan to blow up New York City landmarks. Egyptian religious scholar Omar Abdel Rahman was sentenced to life in prison in 1995. He was also the spiritual leader for the men convicted in the 1993 bombing at the World Trade Centre. In the California case, information about the informant who spied on the Islamic Centre of Irvine came out last week at a detention hearing for a brother-in-law of Osama bin Laden's bodyguard, an Afghan native and naturalized US citizen named Ahmadullah Niazi. Niazi, 34, was arrested Feb 20 on charges of lying about his ties to hardline groups on his citizenship and passport applications. He will be arraigned Monday in US District Court in Santa Ana, Calif. FBI Special Agent Thomas J Ropel III testified at the hearing that an FBI informant infiltrated Niazi's mosque and several others in Orange County and befriended Niazi. Ropel claimed the informant recorded Niazi on multiple occasions talking about blowing up buildings, acquiring weapons and sending money to the Afghan Mujahideen. Local Muslim leaders say they had suspected since at least 2006 that the FBI was trying to infiltrate the Islamic Centre and other Muslim organisations. Some community leaders, worried that they were being watched, filed a Freedom of Information Act request with the FBI in 2006 seeking surveillance records on themselves. They are still engaged in litigation over the request, said Shakeel Syed, Executive of the Islamic Shura Council of Southern California. "We suspected this was happening," said Syed, who suspects his home and office phones are wired. "What these guys have done is create an environment where every person begins to suspect the other, and with the infighting and inward suspicion, the community becomes its own victim." A spokeswoman for the FBI's Los Angeles bureau, Lourdes Arocho, had no comment. Former FBI agents, however, said that although the law places almost no constraints on the use of informants, the agency takes sending an informant into a mosque very seriously and imposes a higher threshold for such requests.