Pugoda: A fresh blast was heard on Thursday in the town of Pugoda, which is 45 kilometres away from Sri Lanka's capital Colombo. The police are investigating the explosion and have stated that no casualties have been reported so far.

News agency Reuters reported that the blast was heard from a vacant plot of land just behind the magistrate's court in Pugoda.

The blast comes amidst high tension in the country following blasts across the island nation on Easter Sunday.

At least 359 people have lost their lives and over 500 have been injured in the blasts that took place in three churches and four hotels.

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Sri Lanka's defence minister Ruwan Wijewardene addressed the media and said that the group that unleashed Sunday’s attacks was a nine-member gang including one woman. He added that the suicide bombers who detonated explosives were a radical splinter group that broke off from the local terror outfit National Thowheeth Jama'ath.

In the media briefing, Wijewardene said that the suicide bombers were "quite well educated" and had even "studied in the UK and Australia, before returning to Sri Lanka".

The defence minister stated that eight of the nine suicide bombers had been identified and they believe that ninth one is dead.

On Wednesday, the nation’s Parliament passed regulations giving emergency powers to the police and military to detain suspects, and for the fourth day in a row, authorities imposed a nationwide night-time curfew.

The Washington Post reported that two top national security officials stepped down on Wednesday as a response to the failure in acting on the intelligence warnings that were given to the country ahead of the attacks.

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Sri Lanka's President Maithripala Sirisena ordered the country's police chief, Pujith Jayasundara and top civil servant of the defence ministry, Hemasiri Fernando, to step down.

Defence minister Ruwan Wijewardene said in a press conference that at least 60 persons, all of Sri Lankan nationality have been arrested for questioning.

Reports came in that the Islamic State claimed responsibility for the attacks. The message came through the outfit's media forum Amaaq, however Sri Lanka's defence ministry has not denied the claim nor accepted it.

Wijewardene said, "There could be connection through ideology and maybe funding", but he asserted that it is still under investigation and can't be made certain.

Wijewardene also added that the intelligence agencies are probing if the attacks were in retaliation to the Christchurch attacks in New Zealand where Muslims were targeted while offering Friday prayers. But there has been no word so far about the progress on this angle.