ISLAMABAD, Pakistan — A Pakistani Muslim spiritual leader known as the “father of the Taliban” was killed Friday evening by a knife-wielding attacker who sneaked into his bedroom, officials said, further roiling the country’s combustible religious tensions.

The leader, Maulana Sami ul-Haq, 81, exerted an overarching influence over the Taliban movement in neighboring Afghanistan and within Pakistan and led his own faction of a religious party, Jamiat Ulema-e-Islam.

“He has been stabbed to death,” said Fawad Chaudhry, the country’s information minister.

There was no immediate claim of responsibility, and the circumstances of the killing were unusual. Mr. Haq was resting at home in the city of Rawalpindi adjacent to Islamabad when he was stabbed.

Police officials said an unidentified assailant entered the house while Mr. Haq’s personal staff members were at a nearby market. They said the attacker went into Mr. Haq’s bedroom, stabbed him in the chest and shoulder multiple times and left.