Pakistani officials have dismissed the allegations and have asked for evidence from Iran.

“If Iran has evidence that elements from Pakistan are involved in activities against Iran, they should share it with us,” Ms. Aslam said Friday during a weekly press briefing. “Our information is that these incidents took place inside Iranian territory by Iranians and that is corroborated by their own accounts. It is not helpful to externalize problems,” Ms. Aslam said.

On Saturday, the situation at the border remained volatile. Provincial officials in Pakistan said Iranian soldiers launched five mortar shells at a Pakistani security post in the Mashkel area of Baluchistan. No casualties were reported.

The border problems with Iran come as Pakistan is also facing growing tensions with India on its eastern border. In recent weeks both countries have accused each other of initiating shooting and mortar attacks along the disputed border of Kashmir. At least 17 people have died and dozens have been wounded this month as Pakistani and Indian forces traded fire on both sides of the Kashmir frontier.

On Saturday, the Pakistani army chief, Gen. Raheel Sharif, speaking during a parade of army cadets in the northern town of Abbottabad, vowed to defend the country against external aggression, although he did not specifically name any countries.

“Sentiments of good will and amity notwithstanding, let there be no doubt that any aggression against our beloved country will get a befitting response and no sacrifice will be too great in this sacred cause,” Gen. Sharif said. “We desire regional stability and relationship based on equality and mutual respect.”