Sri Lanka President Maithripala Sirisena issued a gazette notification on Tuesday, banning three extremist groups – National Thowheed Jamaath, Jammiyathul Millathu Ibrahim and Willayath As Seylanil, reported.

The Islamic State group had claimed responsibility for the terror attacks on Easter Sunday which claimed 253 lives. However, Sri Lankan investigators had blamed the National Thowheed Jamath for the attacks. They had also accused the Jammiyathul Millathu Ibrahim of assisting the group.

Sirisena also prohibited the use of drones in the country until further notice, PTI reported. The president had imposed an Emergency last month, and took Tuesday’s decisions based on Emergency provisions.

Police media spokesperson SP Ruwan Gunasekara said a curfew will be imposed all over the country from 9 pm. The curfew will be in place till 4 am on Wednesday.

The police arrested nine people for allegedly inciting violence in the Minuwangoda area near Negombo city. They were produced before the Minuwangoda magistrate’s court and remanded in custody till May 29.

The United Nations, meanwhile, asked the government to exercise its powers under Emergency provisions in a “proportionate and non-discriminatory manner that would respect the rights of all communities”, The Sunday Times reported. “The United Nations calls on the authorities to hold the perpetrators and inciters of violence to account,” the statement said. It also asked people not to spread misinformation.

On April 21, nine suicide bombers carried out a series of blasts at three churches and several luxury hotels. On April 26, Sirisena had said that Zahran Hashim, who allegedly played a key role in the blasts, had died in the explosion at the Shangri-La hotel.

The Sri Lankan Police have arrested over 1,000 people since the attacks took place. Police officials say that all those responsible for the blasts have either either been killed or arrested.

On Monday, Sri Lanka imposed a nationwide curfew after mobs attacked mosques and shops of Muslim owners. The government also temporarily blocked social media and messaging apps, including Facebook and WhatsApp after a mosque was attacked in Chilaw.

Almost 10% of the nation’s population are Muslims while the majority are Sinhalese Buddhists.