Pakistan clamps down on group tied to Lashkar

Among the Jamaat ud-Dawa leaders placed under house arrest for three months was Hafiz Saeed, who founded Jamaat and Lashkar-e-Taiba, the Pakistani militant group suspected in the attacks in India's financial capital late last month. He had been operating openly in the eastern city of Lahore, where he told reporters that Jamaat ud-Dawa was not involved in terrorism.

Since the Mumbai attacks, in which more than 170 people were killed, Pakistani authorities have been under immense pressure from the U.S. and India to take significant action against Lashkar militants. Their response is seen as crucial to defusing the tension between nuclear-armed rivals Pakistan and India.

The Pakistani government detained several Lashkar leaders this week, but its move against Jamaat ud-Dawa, which bills itself as strictly a relief agency, was unprecedented.

Still, Islamabad's traditional reluctance to curb anti-Indian militants left room for doubt as to whether the pressure would last.

"We'll have to wait and see what happens after the crackdown," said Samina Ahmed, the South Asia project director for the International Crisis Group. "It's not enough to just arrest them."

The U.N. Security Council on Wednesday declared Jamaat a terrorist group, saying it was directly linked to Lashkar, and imposed sanctions on the group, including a travel ban.

The attacks in Mumbai have increased tensions between Pakistan and India to their highest point since 2002, when the countries sent a combined 1 million troops to their border.

On Thursday, Indian officials announced that they wanted Pakistan to turn over 40 suspected militants, doubling their list from the week before. Pakistani authorities have said they will not turn over anyone, and they have demanded that India provide evidence regarding suspects in the attacks.

In New Delhi on Thursday, lawmakers demanded that Pakistan act aggressively to curb militancy. Home Minister Palaniappan Chidambaram described Pakistan as the "eye of the storm" of terrorism in South Asia and reiterated India's assertion that "the finger of suspicion unmistakably points to the territory of our neighbor" in the attacks on Mumbai.