The input was sent through diplomatic channels to the island nation after a through investigation pertaining to the ISIS case in Coimbatore was carried out by the NIA, which has filed a charge sheet against seven people.
During investigation, the probe team had stumbled upon videos of National Thowheed Jamaat (NTJ) leader Zahran Hashim, which was indicative of a terror attack on the Indian High Commission in Colombo.
After further investigation which included cyber trailing of some of the accounts associated with the ISIS, the central security agencies shared an input with their Lankan counterparts about the churches being the likely target of the ISIS module, they said.
Over 350 people were killed in Sunday's serial blasts at churches and hotels.
The videos, seized from the accused in the Coimbatore case, showed Hashim asking youths from Sri Lanka, Tamil Nadu and Kerala to establish an Islamic rule in the region.
The arrested accused, who have been charge-sheeted since then, include Mohamed Ashiq A, Ismail S, Samsudeen, Mohammed Salauddin S, Jafar Shadik Ali and Shahul Hameed.
The case was originally registered at B3 Variety Hall Police Station, Coimbatore City on September 1 last year and pertained to the criminal conspiracy hatched by the accused with the intention of furthering the objectives of the proscribed terrorist organisation ISIS by targeting Hindu leaders and activists, who are critical of religious terrorism.
The NIA investigation showed that the arrested persons had got radicalized on the violent extremist ideology of the ISIS and they had been propagating the same ideology over the social media.
With the intention of furthering the objectives of the terrorist organisation ISIS in India, the accused had organized themselves into a terrorist gang in June, 2018 and conspired to further the activities of the group by carrying out terrorist attacks targeting persons critical of the proscribed terrorist organisation and its violent extremism ideology.
The accused in Coimbatore case were in touch with Hashim for being enrolled in the ISIS terror group.
Though the investigation in the case are complete, the officials did not rule out the possibility of questioning all the six accused again in case some evidence suggested that they had any knowledge about the blasts in Sri Lanka