Quoting a senior police official who wished not to be named, Pakistan's largest English daily Dawn reported that the two had been arrested after designation from three other suspects who were already in police custody.
A report sent by the state government of southwestern Baluchistan province to Islamabad in November claimed the militant network had recruited 10,000 to 12,000 militants from Hangu and Kurram Agency tribal areas.
The report said ISIL had offered "elements" from Tehrik-e-Taliban Pakistan, or TTP, a conglomerate of different insurgent groups operating in Pakistan, and hardline Sunni militant group Lashkar-e-Jhangvi, to join its ranks to attack security installations and the minority Shiite community in Pakistan.
The network has also formed a strategic planning wing to establish its bases and recruit followers in Pakistan, the report issued by the home department of Balochistan government stated.
Pakistan's Khyber Pakhtunkhwa and Balochistan provinces must be prepared for possible ISIL attacks near the border with Afghanistan, the document said.
The warning had been issued weeks after six key Taliban commanders, including former TTP spokesman Shahidullah Shahid, announced their allegiance to ISIL leader Abu Bakr al-Baghdadi in November.
However, several security analysts have indicated that the report was riddled with exaggerations.