ISLAMABAD, PAKISTAN - Afghan President Hamid Karzai inflamed relations with Pakistan on Sunday by threatening to send troops there to hunt down Taliban fighters who find sanctuary across the border.

Karzai alleged that Pakistan was secretly supporting the Taliban, including providing a refuge for the group's leader, Mullah Omar. The United States, coming under heavy attacks in Afghanistan, has also accused Pakistan, supposedly a key ally in the anti-terror fight, of providing shelter for militants. Pakistan has angrily rejected the charge.

"Afghanistan has the right to destroy terrorist nests on the other side of the border in self-defense," Karzai said, speaking to reporters in Kabul. "When they cross the border from Pakistan to come and kill Afghans and coalition troops, it gives us exactly the right to go back and do the same."

Pakistan was already outraged over the deaths last week of 11 of its paramilitary troops, hit in a U.S. airstrike near a border checkpoint.

The United States and Afghanistan are deeply concerned that the Taliban uses Pakistan's tribal border region, called the Federally Administered Tribal Areas, to launch attacks in Afghanistan and then retreat back into Pakistani territory, beyond the reach of coalition and Afghan troops. But it was the first time that Kabul had warned that it would send troops over to deal with the problem itself.

Those concerns have been further heightened by Pakistan's new policy of negotiating peace deals in the tribal region, aimed at stopping attacks by the militants within Pakistan. The accords, some fear, could result in the Pakistani army pulling out of the tribal areas, freeing its warlords, including the self-declared Taliban leader in Pakistan, Baitullah Mehsud, to focus on fighting in Afghanistan.

'We will go after him'

"Baitullah Mehsud should know that we will go after him now and hit him in his house," Karzai said.

The Afghan president is under immense pressure to improve law and order at home, with his government reeling from a massive jailbreak on Friday from Kandahar, in which about 400 Taliban were freed after insurgents blew their way into the city's prison.

In Pakistan, Karzai's threats Sunday were seen as distraction tactics.

"This is a lot of bluff," said Talat Masood, a retired Pakistani general. "He is trying to deflect attention from the inadequacies of governance and lack of security in Afghanistan."

Analysts said that, given the military challenges Karzai faces at home, an incursion into Pakistan was unrealistic.

But the Pakistani government reacted sharply to Karzai's comments. "We will neither interfere in the internal affairs of any country, nor will we allow anyone to interfere in our affairs," Pakistani Prime Minister Yousaf Raza Gilani said.