Indian police said they have arrested a Facebook friend of the suspected mastermind of the Easter Sunday bomb attacks in Sri Lanka for spreading the ideology of the militant Islamic State group on social media to recruit young people to participate in a terrorist attack in southern India.

A criminal case was filed against Mohammed Azarudeen after authorities raided his home in the Indian state of Tamil Nadu on Wednesday, according to the National Investigation Agency, which oversees counterterrorism efforts.

Authorities conducted six other raids and took five other people in for questioning, it said in a statement Friday. It said Azarudeen was friends on Facebook with Zahran Hashim, the alleged leader of the suicide bomb attacks in Sri Lanka on Easter that killed more than 250 people.

The statement said Azarudeen and other members of his group shared “radical contents” attributed to Hashim on a Facebook page.

Hashim, who died along with six others after detonating bombs at three churches and three high-end hotels in Sri Lanka, was known for violent speeches in the Tamil language on social media that Muslim community leaders said they had flagged to authorities long before the attack.

Indians from Tamil Nadu share cultural and linguistic ties with Sri Lanka's ethnic Tamil community.

Police were investigating suspected sympathisers of the militant Islamic State group in southern India when they stumbled onto the Easter plot. India shared intelligence about the people involved in the plan and some of the targets with officials in Sri Lanka at least three times before the April 21 attack.

A Sri Lankan parliamentary committee is continuing a closed-door probe of the intelligence lapses, over objections by President Maithripala Sirisena that evidence from the investigation is too sensitive for public release.

The Islamic State group took responsibility for the blasts and has since claimed involvement in several smaller attacks in South Asia, including a grenade attack on traffic police in Dhaka, Bangladesh, and a gunbattle with security forces in Indian-occupied Kashmir. Authorities said they are still determining the extent of the group's involvement.

Since the Sri Lanka attacks, India's National Investigation Agency has begun, in an unprecedented manner, to publicise its crackdown on suspected Islamic State group supporters, including the May arrest of a 29-year-old man who they said was a follower of Hashim and was plotting a suicide bombing in the southern Indian state of Kerala.

Former Indian military and intelligence officials say the Islamic State group does not appear to have much of a foothold in India, but that the diminished militant group is far from defeated.