The authorities claim to have arrested an Indian national and five Pakistanis who were said to be planning a terror attack on a police academy near the adjacent garrison town of Rawalpindi.
While the Indian national was arrested on Friday morning, the other five were arrested later in the day on the basis of information provided by him, Dawn News channel said on Saturday.
It said the group was planning to attack the police college at Sihala that lies within the Islamabad federal capital territory.
"The Indian was wearing five thick shirts and a belt," the channel quoted a police official as saying, adding that he was arrested on suspicion after being seen in the area.
An investigation team has been set up to question him, deputy inspector general of police and college commandant Fateh Sher Joyia told Dawn News.
Maps of important Pakistani cities along with some phone numbers were recovered from his possession, Joyia added.
"Sources said the alleged Indian spy admitted that he and others were planning terror attacks on the police college," the channel said.
Officials declined to give the name and other information on the Indian, saying details could be shared only after the investigations had been completed.
Curiously enough, no further details are available about a blast followed by firing late Friday near the Manawan police training academy on the outskirts of Lahore.
Gunshots were heard half a kilometre from the academy, an eyewitness said.
Heavily armed gunmen had attacked the academy on March 30, holding some 400 trainees hostage for nearly eight hours before the security forces recaptured the complex. Eight trainees, an equal number of attackers and two civilians were killed in the assault.