KABUL, Afghanistan — Afghanistan's top intelligence chief and interior minister abruptly resigned on Sunday after President Hamid Karzai criticized the pair for failing to stop last week's attack on a nationwide peace conference as the president was addressing the gathering.

Amrullah Saleh, the director of Afghanistan's powerful intelligence agency, and Hanif Atmar, the head of the interior ministry — which oversees the nation's beleaguered police force — stepped down after a tense meeting with Karzai.

"The president of Afghanistan has lost trust in our capabilities," said Saleh, the head of the National Directorate of Security, on Sunday, after conferring with Karzai at the presidential palace.

The cabinet shake-up comes as U.S.-led military forces are gearing up for a summer offensive against Taliban fighters in southern Afghanistan.

Saleh and Atmar were both regarded by many Western officials as strong allies in the push to transform the Afghan government into a respected political force that won't have to rely on international forces of more than 100,000 troops to prevent the Taliban from again seizing power.

Their removal could weaken security ties between Karzai's cabinet and the international community, said Thomas Ruttig, a co-director of the Afghanistan Analysts Network, an independent international research organization.

"The sacking of Saleh is a blow for the U.S., which had put a lot of resources into the (Afghan intelligence agency) and apparently had good intelligence cooperation with (it)," Ruttig said.

Saleh, a key Northern Alliance leader and ethnic Tajik from the country's Panjshir Valley, spent more than six years as the intelligence chief and worked closely with his Western counterparts.

Atmar, an ethnic Pashtun who's served in Karzai's governments since 2002, was tapped nearly two years ago to take over the Interior Ministry as part of a cabinet shuffle.

As interior minister, Atmar was responsible for overseeing transformation of the widely criticized police force considered essential to President Barack Obama's plant to begin withdrawing U.S. forces from Afghanistan in 13 months.

U.S. Army Gen. Stanley McChrystal, the head of coalition military forces in Afghanistan, said he respected Karzai's ability to take the "difficult political decision" to replace the two men.

"I remain confident in President Karzai's leadership and his ability to appoint credible replacements to lead these critical organizations," McChrystal said in a statement.

Karzai, who is also an ethnic Pashtun, sometimes has had a frosty relationship with the two ministers, and things apparently came to a head on Sunday.

For more than two hours, Karzai asked the ministers to explain how at least two militants had managed to evade smothering security measures designed to protect 1,600 Afghan leaders who took part in the three-day assembly in Kabul.

While the pair tried to defend their actions, Karzai was dissatisfied with their response, prompting Atmar and Saleh to submit their resignations, said presidential spokesman Waheed Omar. Karzai accepted and immediately named their deputies as temporary replacements.

"We had a tough conversation," said Saleh, who suggested that the attack was just one reason among many for his resignation. Martine van Bijlert, the other co-director of the Afghanistan Analysts Network, said that Karzai may have used the attack as an excuse to get rid of two men he considered unreliable.

However, Omar said that Karzai couldn't accept their inability to prevent Wednesday's assault.

The Interior Ministry said Sunday that the attackers were part of the Haqqani network of Taliban allies that's staged a series of dramatic attacks on the Afghan capital in recent years.

Two of the attackers evaded detection by pretending to be a couple out for a walk, with one of the men wearing a burqa to conceal his identity, said Interior Ministry spokesman Zemiri Bashary.

The pair were able to walk more than a mile through heavy security and get close enough to target the massive tent while Karzai was delivering a nationally televised appeal for the Taliban to put down their weapons.

The rockets missed their targets, but the assailants managed to keep fighting Afghan forces for more than 45 minutes. Afghan forces killed two men and took a third in for questioning.

The Taliban took credit for the attack, which cast a pall over the event. The assembly ended Friday by endorsing Karzai's attempts to spark peace talks with Afghan insurgents.

(Shukoor is a McClatchy special correspondent.)

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