Bangkok, Thailand ? Hambali, alleged mastermind of al-Qaida’s campaign of bombings in Southeast Asia, was plotting new terror attacks when he was captured last week, possibly against a Bangkok summit President Bush is due to attend, Thailand’s prime minister said Saturday.

Hambali, an Indonesian whose real name is Riduan Isamuddin, had planned to make Thailand a base for terror operations, but his arrest — and those of three of his associates since June — has uprooted his terror network Jemaah Islamiyah from the country, the Thai leader said.

Thailand’s porous, jungle and river frontiers and lax security at border posts made it a tempting place to hide for Jemaah militants. But its cells have been more prominent in other nations of the region — Malaysia and Indonesia. Indonesia — scene of the group’s deadliest bombings — hiked up security, fearing revenge attacks during Independence Day celebrations this weekend.

The Asia-Pacific Economic Cooperation forum, set for Oct. 20-21 in the Thai capital, is expected to draw at least 20 world leaders, including Bush.

“The result of investigations show that Hambali came to Thailand not only to seek a safe haven but he also planned to make a move during the APEC meeting,” Prime Minister Thaksin Shinawatra told reporters. He refused to elaborate.

“He came here to work and was using Thailand as a base for committing acts of terror. Investigations reveal some connection to APEC, but we still have to investigate further,” Thaksin said.

The 39-year-old Islamic cleric was captured by CIA agents and Thai forces in a raid Monday on his apartment in the ancient temple city of Ayutthaya, 50 miles north of Bangkok. Thai military sources say he was handed over to U.S. investigators and flown out of the country on Wednesday. Thaksin would not comment on Hambali’s whereabouts.

U.S. investigators will seek to determine if Hambali had any success in recruiting new suicide hijackers — an assignment he was given soon after the Sept. 11 terror attacks in the United States, according to a Bush administration official.

Hambali, said to have trained in the 1990s under Osama bin Laden in Afghanistan, is reported to have been close to Khalid Shaikh Mohammed, the Sept. 11 organizer captured earlier this year, and is believed to have played host in January 2000 to a meeting of senior al-Qaida operatives, including two Sept. 11 hijackers, in Kuala Lumpur.

But in Southeast Asia, he is seen foremost as the militant who brought al-Qaida-style attacks to several countries in the region, including the October suicide bombings in Bali, Indonesia, that killed 202 people, mostly foreign tourists.

Thaksin said the arrests of three Hambali associates in recent months led to Asia’s most wanted man. Among those caught by Thailand was Zubair Mohamad, a Malaysian believed to have been instrumental in Jemaah Islamiyah’s financial dealings, Thai and Malaysian newspapers reported Saturday.

The trail began exposed by an “irregular money transaction” noticed by investigators, the Thai premier said in his weekly radio address to the nation.

This “resulted in the arrest of the first case, the second, the third, and now we have got the fourth man — Mr. Hambali — who is regarded as the last one in our land,” he said.

“Finally we have got them all,” he said.

Jemaah Islamiyah is also blamed for the Jakarta Marriott Hotel bombing on Aug. 5 that killed 12 people, as well as attacks on churches in the Philippines and foiled plots to attack diplomatic missions in Singapore.