Located in Pakistani-administered Kashmir, the camp was formerly home to Lashkar-e-Taiba, a militant Pakistani organization, intelligence and government officials told the Associated Press Monday. Among those reportedly arrested was Zaki-ur-Rehman Lakhvi, suspected of leading the group responsible for the attacks.
Later media reports differed as to whether Lakhvi had actually been seized, with some officials backing off the earlier claim.
In May, the U.S Treasury Department alleged that Lakhvi directed Laskhar-e-Taiba operations in Chechnya, Bosnia and Southeast Asia. In 2004, he allegedly sent operatives and funds to attack U.S. forces in Iraq, it said, according to the AP.
The camp was being used by Jamaat-ud-Dawa, a charity organization thought to be a front to Lashkar-e-Taiba. A gunman arrested in the Taj Mahal hotel in Mumbai last week gave the name of the Lashkar organization and cited Lakhvi as its leader.
The New York Times quoted unnamed American intelligence and counterterrorism officials Monday as saying that Pakistan's spy service, the Directorate for Inter-Services Intelligence, or ISI, has allowed intelligence sharing and other protections for Lashkar-e-Taiba, allowing it to grow in recent years.
Lashkar-e-Taiba was initially founded some 20 years ago with the fostering of Pakistani intelligence officers to help challenge Indian control of portions of the disputed region of Kashmir.
"People are having to go back and relook at all the connections" between government and militant groups, an American counterterrorism official who spoke on the condition of anonymity told the Times.
The Pakistani government has adamantly denied any ties to militant organizations. Pakistan banned Lashkar-e-Taiba in 2002, but there have been few if any convictions of its members since then.
Amid civilian protests and accusations of Pakistani involvement, government officials have promised to assist American and Indian investigations in any way they can.
Sunday's raid was Pakistan's first public response to U.S. and Indian demands for the arrest of the perpetrators of the Mumbai attacks, which have sharply raised tensions between South Asia's two nuclear-armed powers.
"The government of Pakistan has always said it would act on any evidence that is presented to us," another unnamed source told the Times. "We will make sure that nobody uses Pakistani territory to carry out military activity."
U.S. Secretary of State Condoleezza Rice said Sunday that the attackers had likely spent time in Pakistan.
"I think there's no doubt that Pakistani territory by probably non-state actors," Rice told CNN's "Late Edition" Sunday.
Lashkar's ties to terrorist organization al-Qaida are unclear. While senior al-Qaida officials have been known to use Lashkar safe houses as hide-outs, Lashkar is not believed to have merged its operations with the group, the Washington Post reported.
Some have expressed concern since Pakistan's raid on the camp that the Pakistani police will not cooperate properly with investigations.
"We've seen before how Pakistan will arrest some militants, keep them for a couple of months and then release them when the world's not paying attention," B. Raman, a former head of the Pakistan desk at the Research and Analysis wing, told the Times of London. "It must not be allowed to do that this time. They have to prosecute these people and dismantle the whole terrorist infrastructure."
Officials are still considering other suspects in the attacks, which killed 171 people, according to the New York Times. Indian police said they were holding a man arrested in Northern India last February for questioning on links to Islamist militant groups in the region.
When arrested, the suspect was found carrying maps of Mumbai that highlighted many of the targets that were hit during the siege.
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