Sri Lanka on Saturday banned local Islamist extremist outfit NTJ and a splinter group, which are linked to the ISIS that has claimed the responsibility for the Easter bombings that left 253 people dead and several hundreds injured.

National Thawheed Jammath (NTJ) leader Zahran Hashim, the mastermind behind the attacks, was killed inside the Shangri La hotel where he detonated himself.

"All movable and immovable property of these two organisations will be confiscated," the statement said.

The move to ban the outfits came after the Lankan Parliament adopted a newly-enforced emergency regulation on Wednesday following a series of eight coordinated blasts, which ripped through three churches and three high-end hotels frequented by tourists on April 19 in the country's deadliest violence since the devastating civil war ended in 2009.

Prime Minister Ranil Wickremesinghe on Friday said the country needs new laws to deal with threats posed by local terror outfits linked to ISIS.

"The definition on aiding terrorism is very narrow. Therefore, the laws are not strong to deal with a situation like this. We have to widen the scope of these laws to counter global terrorism. Not only they (the terrorists) should be arrested, their assets also need to be confiscated," he said in a televised address.

The Islamic State group has claimed responsibility for the Easter terror attacks on three Catholic churches and three luxury hotels but the government has blamed a local Islamist extremist group, National Tawheed Jamath (NTJ), for the bombings.