ISLAMABAD, Pakistan — Hamid Mir, a prominent Pakistani journalist and a critic of the nation’s powerful military, was wounded by gunmen in the southern port city of Karachi on Saturday evening, according to police officials and local news media reports.

There was no immediate claim of responsibility, but within hours of the attack, Amir Mir, Mr. Mir’s brother, accused the chief of the intelligence service, the Inter-Services Intelligence directorate, or ISI, of being behind it.

In an emotional outburst on Geo TV, the network on which Hamid Mir hosts a popular talk show, Amir Mir assailed the intelligence agency, saying that the ISI “was eating up Pakistan like termites” and accusing its director, Lt. Gen. Zahir ul-Islam, and other ISI officials of planning to kill Mr. Mir.

He said that his brother had told him about two weeks ago that his life was in danger and that he had recorded a video that had been sent to the Committee to Protect Journalists.