A top U.S. counterterrorism official said Saturday that parts of Pakistan are a "safe haven" for militants and Usama bin Laden was more likely to be hiding there than in Afghanistan.

Henry Crumpton, the U.S. ambassador in charge of counterterrorism, lauded Pakistan for arresting "hundreds and hundreds" of Al Qaeda figures but said it needed to do more.

CountryWatch: Pakistan

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"Has Pakistan done enough? I think the answer is no. I have conveyed that to them, other U.S. officials have conveyed that to them," he told reporters at the U.S. Embassy in Kabul after talks with Afghan officials.

The chief spokesman for Pakistan's army, Maj. Gen. Shaukat Sultan, dismissed Crumpton's assertion that Islamabad was not doing enough.

"It is totally absurd," he said. "No one has conveyed this thing to Pakistan, and if someone claims so, it is absurd."

Crumpton said U.S. officials continue to believe that bin Laden is somewhere along the Afghan-Pakistani border, and was more likely to be on the Pakistani side.

"If we knew exactly where bin Laden was, we'd go get him," Crumpton said. "But we're very confident he's along the Pakistan-Afghan border somewhere," he said.

He added that there was a "higher probability" that the Al Qaeda leader was hiding on the Pakistan side.

Crumpton also gave Islamabad credit for last year's capture of a top Al Qaeda strategist with a $5 million bounty on his head.

U.S. and Pakistani officials said earlier this week that Mustafa Setmarian Nasar was arrested in the southwestern Pakistani city of Quetta in November. Crumpton said that this showed that Pakistan is working to arrest Al Qaeda leaders.

Pakistan has launched repeated counterterrorism operations in its lawless tribal regions close to the Afghan border over the past two years, in which hundreds of militants and soldiers have died.

"Our expectation is that they will continue to make progress, and we know that it's difficult," he said. Pakistan "can't remain a safe haven for enemy forces, and right now parts of Pakistan are indeed that."

A senior security official in Islamabad said that Crumpton, during meetings with Pakistani intelligence and government officials this week, praised Pakistan for its efforts to hunt down militants.

"I am surprised that he praised us here, and is saying something else in Kabul," the official said on condition of anonymity because he was not authorized to speak on the record.

The official added that Gen. John Abizaid, the chief of the U.S. Central Command, also thanked Pakistan when he met with Pakistani leader Gen. Pervez Musharraf on Thursday.

Separately, gunmen on a motorcycle killed a former regional Taliban leader who switched allegiances after the hard-line regime was ousted in southwestern Pakistan on Saturday, police said.

Mullah Samad Barakzai, who was head of the Department for Promotion of Virtue And Prevention of Vice in Afghanistan's southern Helmand province during the Taliban's hard-line rule, was standing near a seminary in Quetta when he was attacked, local police chief Qazi Abdul Wahid said.

He said Barakzai, also known as Maulvi Yar Mohammed, had been living in Pakistan since the Taliban regime was ousted in late 2001 as a result of U.S.-led attacks.

The man had distanced himself from the Taliban and become a supporter of Afghan President Hamid Karzai's government, Wahid said.

"It seems that he has been killed by Taliban," he told The Associated Press.