ISLAMABAD, Pakistan — Opposition to Pakistan’s American-allied president intensified yesterday after weekend violence killed 41 in the nation’s business capital, with a strike closing shops across the country and lawmakers denouncing President Musharraf as “killer Musharraf.”

The unrest dramatically raised the stakes for General Musharraf, whose attempts to extend his nearly eight-year rule are being threatened by his suspension two months ago of the independent-minded Chief Justice Iftikhar Mohammed Chaudhry.

Opposition parties and many ordinary citizens blamed General Musharraf and his political allies for the bloodshed in Karachi on Saturday, when rival political groups staging rallies over a visit by the judge to the volatile city clashed in the streets. Security forces failed to intervene.

Gunmen, meanwhile, killed a senior administrator for the Supreme Court, Syed Hamid Raza, at his home in Islamabad before dawn. Police said they believed robbers responsible, and the state news agency quoted the victim’s father as saying the same. A cousin, however, called it a targeted killing because nothing was stolen, but offered no evidence to support his assertion.

The opposition strike call was observed in most of Pakistan’s major cities, including Lahore, Peshawar, and Quetta, but particularly Karachi. The city of 15 million people was paralyzed, with shops closed and traffic thin — but also because local officials banned public gatherings and authorized security forces to shoot rioters on sight.

“What happened in Karachi was shameful for the government,” said Aslam Khan, a general store owner in Peshawar who supported the strike.

In Lahore, about 8,000 people, including lawyers, opposition party members and human rights activists, burned two effigies of General Musharraf. They also chanted “Death to Altaf Hussain,” referring to a leader of the pro-government Mutahida Qaumi Movement, which was heavily implicated in the Karachi violence.

In the National Assembly, more than 100 opposition lawmakers protested the violence by shouting “Killer, killer general, killer!” and “Killer, killer Musharraf, killer!”

The bloodshed marked a sudden escalation in a crisis that began March 9 when General Musharraf suspended Chief Justice Chaudhry for alleged abuse of office — a move critics suspect was designed to head off legal challenges to the general’s plan to ask lawmakers for another five-year term this fall. The government denied the move was politically motivated.

Commentators said the strike was the clearest indication yet that the opposition could mobilize ordinary Pakistanis — not just their own party activists — for an end to military rule.

Meanwhile, gunmen opened fire yesterday on a convoy carrying American and Pakistani military officials near the Afghan border, killing one American and a Pakistani soldier, the Pakistani army spokesman said.

Four Americans and four Pakistani soldiers were wounded.

Major General Waheed Arshad said unidentified “miscreants” — a word usually used by Pakistani officials to describe violent Islamists — fired at the convoy carrying military officials who attended a meeting in the northwestern town of Teri Mangal.

“Efforts are being made to determine from where the firing came from and who carried it out. The area has been cordoned [off ],” he said.

Afghan military officials also attended the talks to discuss recent fighting between Afghan and Pakistani forces that Kabul said killed at least 13 people inside Afghanistan — inflaming already poor relations between Pakistan and Afghanistan.

NATO’s International Security Assistance Force in Afghanistan confirmed one ISAF soldier was killed and four wounded. According to policy, it did not give their nationalities. It said they “were ambushed by unknown assailants.”

NATO said its soldiers were being treated in Afghanistan.