KABUL, Afghanistan - Afghan President Hamid Karzai yesterday removed two of the country's top security officials - each with longtime ties to the Americans - over last week's attack on a national conference to explore peace with the Taliban.

The removals of the interior minister and intelligence chief surprised U.S. officials and may cause major disruption within Afghanistan's intelligence and security establishment at a critical juncture - as the U.S. and NATO escalate the war and the Afghan government commits to offering peace to the insurgents. The move is likely to fuel speculation over differences within the Karzai administration over its efforts to reconcile with the Taliban - including the possible release of hundreds of detained militant suspects.

The head of the National Directorate of Security, Amrullah Saleh, was a senior figure in the Northern Alliance that helped the U.S. oust the Taliban regime in 2001. As a young man, Interior Minister Hanif Atmar served in Afghanistan's Communist-era intelligence agency and fought mujahedeen opposed to the Soviet occupation.

"It's a very significant event. There will be a massive fallout from these resignations both in the Interior Ministry and the NDS as alliances are shuffled," said Candace Rondeaux, senior analyst on Afghanistan for the International Crisis Group think tank.

"They appear to be forced resignations, and reflect significant worries of Karzai's administration over the loyalty of those leading key security agencies in the country," she said.

Replacing the security chiefs comes after Karzai's May visit to Washington. U.S. officials say the Afghan delegation had impressed with their preparations for the visit, widely seen as a boost to Karzai after a turbulent year marred by prolonged controversy over his re-election in a fraud-marred poll last August.