Pakistan's anti-corruption agency has barred the defense minister and nearly 250 other top officials from leaving the country as political turmoil deepens following a Supreme Court ruling that struck down a graft amnesty.

The agency said Thursday that the officials were now under investigation following this week's court verdict, which meant that up to 8,000 graft and other cases dating back to the 1990s have, or will soon be, reopened. The decision has roiled the country's political elite just as the United States is looking for a solid partner to help it fight against Al Qaeda and the Taliban along the Afghan border.

U.S.-allied President Asif Ali Zardari and several of his key aides are among those who benefited from the amnesty deal. Zardari is protected by constitutional immunity from any criminal prosecution, but opponents say they plan to challenge his eligibility for office.

Pakistan's anti-corruption agency said 247 people who had cases withdrawn under the amnesty had been blocked from travel because cases against them were now under investigation. It did not say who was on the list, but Pakistani news channels reported that Interior Minister Rehman Malik — a key aide of Zardari — was included, as well as Defense Minister Ahmed Mukhtar.

Mukhtar told a local television station that immigration officials at the airport had barred him from boarding a Pakistani International Airlines plane to China along with the navy chief late Thursday. He said he planned to take delivery of a new warship. It was not clear what he was being investigated for.

While the armed forces are under nominal civilian control, analysts say that in reality the top brass — not Mukhtar — make the decisions regarding defense issues. As such, investigations against him and Malik are not expected to directly impact the country's fight against militancy in the border regions.

Wednesday's Supreme Court ruling has significantly weakened Zardari and raised question marks over his future. It has been welcomed by many Pakistanis, who viewed the graft amnesty as an immoral piece of legislation that whitewashed the crimes of the elite.

The 54-year-old, who heads the country's largest party, is already unpopular, in large part because of his close ties with Washington. He now faces the prospect of bruising court battles that will likely mean old corruption charges come under fresh scrutiny.

Zardari's aides said any corruption charges against him were politically motivated and noted that they have never been proved despite being aired since the 1990s. Critics countered he was morally obligated to resign, at least while the court heard any challenges to his rule.

"It will be in his own interest, it will be in the interest of his party and it will be good for the system," said Khawaja Asif, a senior leader from the opposition Pakistan Muslim League party.

The Obama administration needs political stability in Pakistan to succeed in neighboring Afghanistan, where violence against U.S. and NATO troops is running at all time highs. Washington is trying to get Islamabad to crack down on insurgents close to the northwestern border who it says are behind much of the insurgency in Afghanistan.

Earlier Thursday, two U.S. missile strikes pummeled targets in the border region killing 17 people, local intelligence officials said. The latest attacks in more than 40 this year rained down Thursday on North Waziristan, a haven for Al Qaeda and the Taliban, including groups determined to push the U.S. and NATO out of Afghanistan.

It was not immediately clear exactly who or what was the target of the strike, and the Pakistani officials said they were trying to establish the identities of the dead.

In the first strike, two missiles hit a car carrying two suspected insurgents in Dosali village, officials said. Later Thursday, the 10 missiles fired by five drones killed 15 people in two compounds in the Ambarshaga area. At least seven of the dead were foreigners, the officials said on condition of anonymity because they were not authorized to speak to media.

The missile strikes have killed scores of suspected Al Qaeda and Taliban militants, but angering many Pakistanis who point to the resulting civilian casualties. Pakistan regularly condemns the attacks as violations of its sovereignty, but it is believed to secretly aid the U.S. campaign.

The U.S. rarely acknowledges the covert, CIA-run missile program. But when officials have confirmed the attacks, they say the drones are a crucial tool and note that the missiles have slain several top Al Qaeda operatives as well as Pakistani Taliban chief Baitullah Mehsud.

Information from the tribal regions is nearly impossible to independently verify because access to the areas is severely restricted.