Intelligence officials were able to glean information about the plot from the TTP activist arrested recently.

The man, who sources say, hails from Miranshah in North Waziristan, told law enforcement agencies about the two terror suspects who are still at large.

According to the sources, two men from Karachi identified as Nauman and Zakar underwent terror training in South Waziristan and were to carry out attacks on the President's House in Islamabad, the Pakistan Army General Headquarters in Rawalpindi and other defense-related targets.

Intelligence agencies have also compiled a report on the activities of another man — Abid alias Kalia — who is currently active in southern Punjab preparing for a terrorist strike in Lahore.

According to the report, Abid was said to be planning an attack where an explosives-laden vehicle would be used to carry out attacks in the Punjab provincial capital. His targets included the Police Training Center, Inter-Services Intelligence complex as well as army and Rangers installations in the city.

But despite having, what appears to be sufficient information about the terrorists' plans, intelligence and law enforcement agencies have not been able to arrest the man.