The chief suspects in the Bali terror bombings moved undetected through Malaysia and Singapore for years, based at a rural religious school where the parents of students were prodded to donate part of their salaries to help kill Americans.

The school was part of the network built in Southeast Asia by Jemaah Islamiyah, a deadly ally of Al Qaeda, which also used Malaysia -- a modern, moderate country -- to host a meeting in 2000 that brought two of the Sept. 11 hijackers together with other operatives.

Several men who emerged as Jemaah Islamiyah leaders taught at the school -- spiritual chief Abu Bakar Bashir; Imam Samudra, a suspected mastermind of the Bali attacks; Riduan Isamuddin, better known as Hambali; and Mukhlas, the school's top administrator. All are in custody in Indonesia except Hambali.

Indonesian investigators probing the Bali bombings that killed nearly 200 people on Oct. 12 believe that Mukhlas, also known as Ali Gufron, replaced Hambali as the group's chief of operations. Mukhlas was taken into custody late Tuesday in central Java.

All four men are Indonesians who came to Malaysia in the 1980s and '90s to escape the attention of then-dictator Suharto. Living quietly, teaching and seeking recruits, traveling in Southeast Asia and Afghanistan, they established a regional network.

Malaysian authorities say Bashir, Hambali, Samudra and Mukhlas had used the Luqmanul Hakiem school in Ulu Tiram, in the southern state of Johor, since 1993 to spread Al Qaeda's radical brand of Islam.

Selected students and parents, many from affluent families, were told that "Americans are the worst form of infidels and ... enemies of Islam," a senior government official close to the investigation told The Associated Press.

"Parents were told to donate part of their salaries to help Muslim fighters in the region and in Afghanistan to buy weapons to kill as many Americans as possible," the official said, speaking on condition of anonymity.

The school was not registered with state religious authorities and its curriculum is unclear. The official said that teachings of Quranic verses and the need to uphold Islam were followed with more militant themes and solicitations to students and parents.

School officials were not available for comment -- nearly all the teachers are currently either locked up in Malaysia or Indonesia or on the run. The school, shut down earlier this year, is empty now except for a few lizards seen running about.

A glimpse into the faculty mindset came in June, when a Malaysian teacher from the school, Abdullah Daud, testified before the national human rights commission.

Abdullah told the panel that he belonged to Jemaah Islamiyah, had made several trips to Pakistan and Afghanistan, had received military training with the Moro Islamic Liberation Front in the Philippines, and fought Christians on the Indonesian island of Ambon.

"For me, the root issue is that we go up together against the evil people who kill Muslims," Abdullah said. He didn't speak about his role as a teacher.

According to the Malaysian official, the Indonesian radicals preached that Muslims who died fighting Americans would not only go to heaven, but would reserve 70 spots there for relatives and friends. A similar message was delivered at small religious meetings elsewhere in Malaysia and Singapore.

Malaysia would not release the names of students who attended the school. Human rights activists have been in touch with family members of some detained faculty, but said they would keep their whereabouts private.

The most charismatic speakers were Hambali and Mukhlas, the Malaysian official said. Hambali, sometimes described as Al Qaeda's point man in Southeast Asia, has been implicated in operations ranging from logistical support for the Sept. 11 hijackers to bombings in Indonesia and the Philippines.

Singapore authorities believe Hambali handed control of the Jemaah Islamiyah cells to Mukhlas before he went into hiding after Sept. 11.

"Like Hambali, Mukhlas is extremely dangerous," the Malaysian official said. "He's a great motivator and has vast knowledge in assembling bombs."

Amrozi, a brother of Mukhlas and suspected foot-soldier in the Bali blasts, and Samudra were arrested in recent weeks in Indonesia. Bashir -- who denies the allegations against him and says Jemaah Islamiyah does not exist -- was arrested last month in connection with deadly church bombings in Indonesia in 2000.

The school in Malaysia was built to accommodate about 200 students a year, but enrollment may have reached 300 annually, the Malaysian official said. Many parents in Singapore, where Muslims are a minority, sent their children there and gave money to the preachers, the official said.

Ong-Chew Peck Wan of Singapore's Home Affairs Ministry said that it would be "more accurate to say that several Singaporean JI (Jemaah Islamiyah) members sent their children" to the school. She described Mukhlas as the school's principal and the current Jemaah Islamiyah leader for Malaysia and Singapore.

"The school, which catered to children of JI members as well as children of non-JI members, was essentially supported by funds collected by the JI network in both Malaysia and Singapore," Ong-Chew said.

The Malaysian official did not say how much money was collected through the school. Some parents would have known their donations were funding militancy, the official said, while others might have given money in response to appeals to help Islam.

Jemaah Islamiyah's goal is to build an Islamic state across southern Thailand, Malaysia, Indonesia and the southern Philippines, home to about 250 million Muslims.

Though the organization has been around for decades, it was linked to high-profile violence only in recent years -- as it strengthened ties with Al Qaeda and exploited Indonesia's turmoil after Suharto's 1998 downfall. Jemaah Islamiyah leaders left Malaysia and re-based in Indonesia in 1999.

Two years ago, Mukhlas tried to start a second school in Malaysia targeting students from broken homes for recruitment as Jemaah Islamiyah members, the Malaysian official said. The school closed a few months later.

State religious authorities began to probe the original school in 2000 after villagers complained about its teachings.

Borhanaidin Ahmad, who owns a shop nearby, said villagers were uneasy with the Indonesian preachers and the deluge of Singaporean students and parents.

"We did not mix much with them," Borhanaidin said. "There were rumors that the school was teaching all kinds of weird stuff."

But the probe moved slowly and the school's role came to light at the end of 2001, when authorities alerted to a plot to bomb Western embassies in Singapore began rounding up Jemaah Islamiyah suspects. About 100 have been arrested in Malaysia and Singapore.

Several university lecturers who taught at the school were among those arrested in Malaysia. They remain in custody.

Malaysia has been praised by Washington for fighting extremism and there have been no acts of terror in the country, but the topic is highly sensitive. Prime Minister Mahathir Mohamad said a travel advisory issued by the State Department warning of risks of a Bali-style attack lacked evidence and would damage the economy.