Ravi Seneviratne, Director of the Sri Lankan police Criminal Investigation Department (CID), made the comments while testifying before the country's Parliament Select Committee (PSC) probing the April 21 attacks on three churches, three luxury hotels and two other locations.
Seneviratne said the attackers were influenced by the ideology of the IS and it can be concluded that a group that was inspired by the it carried out the bombings, Colombo Page reported.
He told the panel that remnants of the National Thowheeth Jamaath (NTJ), the group that was held responsible by the government for the attacks, had persuaded the IS to claim the bombings.
Seneviratne also said that he was not satisfied with the action taken on the prior warnings received before the bombings one of the most brutal attacks in the island nation since the civil war ended in 2009.
Sri Lanka's former police chief Pujith Jayasundara and former Defence Secretary Hemasiri Fernando are currently facing criminal charges over their alleged negligence in failing to prevent the bombings.
Attorney General Dappula de Livera called the security and intelligence lapses a "crime against humanity".
Last week, Sri Lankan President Maithripala Sirisena claimed that the attacks "were the work of international drug dealers" to disrupt his anti-narcotics drive.
( With inputs from IANS )