ISLAMABAD, Pakistan — Security forces killed as many as 70 militant supporters of a pro-Taliban cleric, the army said Thursday, hours after a suicide attack on an air force bus killed eight and wounded 40.

Opposition leader Benazir Bhutto, seen by many supporters as key to a possible return to democratic rule, flew out of Pakistan to visit family in Dubai, United Arab Emirates, two weeks after she was targeted by assassins upon her return from eight years in exile.

Terror attacks and clashes between militants and President Gen. Pervez Musharraf's security forces have deepened the political turmoil ahead of a Supreme Court ruling on whether Musharraf's sweeping Oct. 6 presidential victory was constitutional. There are fears he could impose a state of emergency if judges rule against him, jeopardizing the country's transition to civilian rule.

"She has gone to Dubai to see her ailing mother and children," Bhutto's spokesman Farhatullah Babar said Thursday afternoon after the former prime minister was seen stepping onto an Emirates plane in Karachi. "She will come back on Nov. 8."

The militants in the northwest district of Swat attacked law-enforcement posts before dawn Thursday, and security forces responded with fire from mortars, small arms and helicopter gunships.

"According to the information I have from police and Frontier Constabulary, between 60 to 70 miscreants were killed in Swat's areas of Khawaza Khela today," army spokesman Maj. Gen. Waheed Arshad said.

The suicide bombing on the Pakistan Air Force bus occurred at around 7 a.m. near an air base in Sargodha, about 125 miles south of Islamabad, air force spokesman Sarfraz Ahmed said. All the dead were air force employees, said Sahid Malik, an official at the hospital treating the victims.

Musharraf, who seized power in a 1999 coup, has pledged to quit the army before starting a new presidential term, but declined on election night to say whether he would accept a negative verdict from the court.

The doubts over his political future and what course he might take if blocked from a new five-year term has added to the climate of uncertainty.

The Supreme Court, which in recent months has emerged as the main check on Musharraf's dominance, said Thursday that rumors of martial law would have no impact on its decision.

"No threat will have any effect on this bench, whether it is martial law or (state of) emergency," said judge Javed Iqbal before adjourning until Friday. The judge warned the next session after that could be Nov. 12, three days before Musharraf's current term expires.

"Whatever will happen, it will be according to the constitution and rules ... No group should think that it can take the Supreme Court hostage," he said.

With his authority and political clout fading, Musharraf agreed to a corruption amnesty to help Bhutto return to Pakistan. That followed months of talks on a possible pro-Western alliance between them to counter Islamic extremism after parliamentary elections slated for January.

Bhutto's Oct. 18 homecoming was the target of the country's deadliest-ever suicide attack, claiming more than 140 lives. Earlier this week a bomber blew himself up near Musharraf's army office in Rawalpindi, a garrison city just south of the capital, killing seven.

There have been no claims of responsibility for the recent attacks, but most have been blamed on Islamic extremists, who also have engaged in the deadly clashes with the military in the volatile northwest.

Musharraf, a key U.S. ally, is under pressure from Washington to crack down on pro-Taliban and al-Qaida fighters hiding in the country's border regions near Afghanistan.

Early Thursday, militants attacked hilltop positions of security forces in the Khwaza Khela area, triggering a gunbattle, said Ali Rahman, a local police official. He added that troops backed by helicopter gunships and artillery continued targeting militant facilities, killing at least five.

The security forces suffered no casualties, he said.

APTN cameraman Mohammed Yousuf in Sargodha contributed to this report.