In a crackdown on the practice, five Malaysian students, including four teenagers, have been jailed without trial here following raids on Islamic boarding schools in Karachi, which had sent them on field trips to get firsthand experience of Islamic militant operations.
The students underwent weapons and explosives training in Afghanistan and Kashmir, and some met al Qaeda leader Osama bin Laden before the U.S.-led Afghan war started in late 2001, Malaysia police told AP.
Three of the five students are the sons of members of an alleged Malaysian cell of Jemaah Islamiyah - the al Qaeda-linked terror network operating throughout Southeast Asia - who were jailed two years ago. A fourth is the brother of a jailed militant suspect.
Hambali, once operations chief for Jemaah Islamiyah, arranged for some of his students to get Pakistan-based training, a senior Malaysian government official told AP, speaking on condition of anonymity. Hambali has been in U.S. custody since August, but ran an Islamic school in Malaysia for years before going on the run shortly before the Sept. 11 attacks in the United States.
His plan was to train future Jemaah Islamiyah leaders, with the students returning home by 2006 to take up jihad, or holy war, said another Malaysian official, also speaking privately.
Hambali, whose real name is Riduan Isamuddin, arranged in 1999 and 2000 for the students to attend Karachi's Abu Bakar Islamic University, paying for at least two students to get there.
In Karachi, they were taken under the wing of Rusman Gunawan, Hambali's brother, who "acted as supervisor" of the Southeast Asian students, a Malaysia security official said.
The five were indoctrinated in an extreme version of Islam in Pakistan and were learning how to attack U.S. targets - including organizing suicide missions - in Malaysia and elsewhere, authorities said. No specific plots were described.
Under interrogation, the students said their instructors told them "they must take up arms, especially against Westerners, as it was the purest form of defending Islam," the Malaysian security official said. "These students were not being trained as foot soldiers but as a second or third echelon of leaders," the official said, speaking on condition of anonymity.
Hambali's brother was among 13 Malaysians and six Indonesians arrested in the Karachi raids in September. Police released eight of the Malaysians after interrogating them, but jailed the others without trial.
The Indonesians, including Rusman Gunawan, were flown to Jakarta and taken into police custody for questioning.
Relatives and lawyers for the students deny their involvement in militant activity, and accuse the government of misusing laws allowing detention without trial for up to two years. Several students have asked Malaysia's High Court to demand police produce evidence to back their claims, or release them.
Rohaimah Salleh, mother of Muhammad Radzi Abdul Razak, 19, is one of the jailed students, said he was sent to the Abu Bakar school to study religion, not terrorism. The teen's teacher father has been detained since December 2001 in a Singapore bombing plot.
"His father felt a solid foundation in religion was very important for our son's future," the mother said. "We had heard from relatives and friends that it was a good school."
The other jailed students are Abi Dzar Jaafar, 18, Mohamad Ikhwan Abdullah, 19, Mohamad Akil Abdul Raof, 21, and Eddy Erman Shahime, 19.
The older relatives of the students are among more than 70 suspected militants being held without trial in Malaysia, many of them in connection with an al Qaeda-linked plot to blow up the U.S. Embassy and other targets in Singapore.
Among those detained is Yazid Sufaat, a former Malaysian army captain and Hambali associate who let al-Qaida operatives, including two Sept. 11 hijackers, use his apartment for meetings in early 2000.
Hambali is accused of masterminding last year's Bali bombings in Indonesia that killed 202 people and a string of other deadly blasts in the region blamed on Jemaah Islamiyah.
Hambali's capture and that of scores of other Jemaah Islamiyah suspects in Singapore and the Philippines has severely curtailed the terrorist network's operations, but a recruiting drive is under way, and key bomb makers are at large.
U.S. officials are following the fates of the Malaysian students closely, including those who have been released, a U.S. Embassy official said.
Hundreds of foreign students, mostly from Southeast Asia, Africa and Arab countries, attend religious schools in Pakistan, where authorities have tightened regulations because of concerns about extremism.
Sidney Jones, whose studies of Jemaah Islamiyah have revealed the use of family ties as a recruiting tool, said Indonesian members had "made a deliberate effort to send their children to known extremist institutions, presumably with the idea of keeping it all in the family for another generation."
The case of the students arrested in Pakistan was "consistent with an effort to ensure that their children came back trained in the same kind of radical jihadist ideology that their parents had," said Jones, of the Brussels-based International Crisis Group.
By Rohan Sullivan and Jasbant Singh