The Indian navy official Kulbhushan Jadhav, 48, committed terrorist acts in Pakistan on New Delhi’s orders.
Pakistani lawyers told this to the International Court of Justice on Tuesday.
They said, he was involved in targeted killings and kidnappings to create anarchy in Pakistan.
Kulbhushan Jadhav is on death row in Pakistan over spying and terror charges.
He was arrested in Balochistan.
Jadhav was sentenced to death by a military court in 2017, with New Delhi dragging Islamabad to the ICJ.
The ICJ issued an urgent order telling Pakistan to stay his execution.
The Indian navy official was carrying out orders given by Indian intelligence agency the Research and Analysis Wing (RAW).
Islamabad’s lawyers opened their case on the second day of hearings at the International Court of Justice.
They are involved in a tense legal stand-off with India in the case of Kulbhushan Jadhav.
Tensions have risen between the two nuclear-armed neighbours after a suicide bombing in Indian-held Kashmir last week.
Pakistan’s Attorney General Anwar Mansoor Khan told ICJ judges that Jadhav ran a network “to carry out despicable terrorism and suicide bombing, targeted killing, kidnapping for ransom and targeted operations to create unrest and instability in the country.”
He said, Jadhav was committing the criminal acts at the behest of the Indian state and the government.
He said, since independence in 1947, India has persistently pursued the policy of trying to destroy Pakistan.
Another Pakistani lawyer Khawar Qureshi told the court, India’s proceedings are for political theatre and should be dismissed.