ISLAMABAD, Pakistan - Despite its crackdown yesterday on a charity group linked to extremists accused in the Mumbai attacks, Pakistan's biggest challenge will be showing that its latest moves against alleged terrorists are more serious and permanent than in the past, analysts say.

Authorities arrested five leaders of Jamaat-ud-Dawa and closed offices in 73 towns and cities where the group once ran schools and clinics, in what critics say was a front for the extremist group Lashkar-e-Taiba. Indian authorities blame Lashkar for plotting the Mumbai attacks, which killed 171 people over three days last month.

Among the five Jamaat leaders placed under house arrest for three months was Hafiz Mohammed Saeed, who founded both Lashkar and Jamaat and who had been operating openly enough in the eastern city of Lahore to give a news conference just hours beforehand.

"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."

In the aftermath of the Mumbai attacks, Pakistani authorities have been under immense pressure from the Unietd States and India to take serious action, which is seen as crucial to defusing the tension between nuclear-armed rivals Pakistan and India. The two countries blame each other for having some role in the deadly attacks.

In the past, when under pressure, Pakistani authorities have rounded up extremists and closed their offices. But the extremists are often kept only under house arrest and usually released quietly months later. Banned organizations have been allowed to change their names and continue operating.

The Pakistani government this week has made unprecedented moves against Lashkar, detaining several of its leaders, and against Jamaat-ud-Dawa, which bills itself as a relief agency. In doing so, Pakistan has been forced to balance international pressure to do more in the war on terror against the pressure of popular opinion among Pakistanis, many of whom regard the popular Jamaat as a charitable group that has done much more for poor people than the government has.

On Wednesday, the U.N. Security Council declared Jamaat a terrorist group, saying it was directly linked to Lashkar and imposing sanctions on the group.

The attacks in Mumbai have increased tensions between Pakistan and India to their highest point since 2002, when both countries sent about one million troops to the border. If the crisis continues, it could distract Pakistan from fighting Taliban-led extremists along its border with Afghanistan.

So far, the two countries seem at an impasse. Yesterday, Indian officials announced they wanted Pakistan to turn over 40 suspects, doubling its wish list from the week before. Pakistan authorities have said they will not turn over anyone. And they have demanded that India turn over evidence if it wants Pakistan to thoroughly investigate.

In a nod to their own intelligence failures with the Mumbai plot, Indian authorities yesterday also announced major changes in their security and intelligence agencies. They want to build an Indian version of the FBI and improve coastal security.

The restructuring will bolster the coast guard and maritime forces, strengthen intelligence agencies with new personnel, establish a national investigative center, and set up training courses for antiterrorism officers, police units and commando squads.

In New Delhi yesterday, lawmakers put on a rare show of unanimity in demanding that Pakistan act aggressively to curb extremists. Home Minister P. 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 our neighbor" in the attacks on Mumbai.

But when a lawmaker pressed the Indian government to declare war, India's foreign minister, Pranab Mukherjee, replied sharply that war was "no solution."

Before the arrests yesterday, Jamaat-ud-Dawa leader Saeed said he would petition the United Nations and international courts to overturn the sanctions on his group. "If India or the U.S. has any proof against Jamaat-ud-Dawa, we are ready to stand in any court," he said. "We do not beg, we demand justice."

Missile Attack Kills 6 in Pakistan

A suspected U.S. missile

strike killed six people yesterday on the Pakistan side of the Afghan border, a region believed to be an al-Qaeda stronghold, two officials said.

Identities

of those killed were not immediately known, the intelligence officials said on condition of anonymity.

"At present, local Taliban

have surrounded the destroyed house, and they are not letting anybody get close to it," said one of the officials.

Citing agents

in the field, the officials said the six were killed in a village near Azam Warsak in South Waziristan.

The United States

is suspected of carrying out more than 30 missile strikes in Pakistan on the Afghan border since August.

- Associated Press