NEW DELHI: The Sri Lankan government on Monday blamed the local Islamist extremist group, the National Thowheeth Jama'ath (NTJ), as being the group that carried out suicide attacks that killed nearly 300 people, the deadliest bombings in the country in a decade.

Government spokesman Rajitha Senaratne, who blamed the NTJ for the attack also said that the Colombo government was investigating whether the group had "international support", news agency AFP reported.

The statement from the government pinning blame on the group came 24 hours after eight serial blasts killed 290 people and injured 500 others.

Separately, Ariyananda Welianga, a senior official at the government’s forensic division, said seven suicide bombers were responsible for the attacks – with two of the bombers blowing themselves up at the luxury Shangri-La Hotel on Colombo's seafront.The others targeted three churches and two other hotels, Welianga was quoted as saying by Reuters news agency.

A fourth hotel and a house in a suburb of the capital Colombo were also targeted, but it was not immediately clear how those attacks were carried out, the Reuters report said.

The NTJ, a radical Muslim group in Sri Lanka, came onto the radar of security agencies last year when it was linked to the vandalisation of Buddhist statues in the island nation, news reports said.

A report in the Times of India said Monday that the Wahhabi aligned NTJ has a significant presence in India’s Tamil Nadu state particularly in districts close to the maritime border with Sri Lanka – something that is expected to worry Indian security experts.

On Sunday, an AFP report from Colombo had said that Sri Lanka's police chief Pujuth Jayasundara had sent an intelligence warning to top officers on 11 April setting out the threat. The warning was quite specific – it had said that the suicide bombers planned to hit "prominent churches," the AFP report said.

It is being suspected that though the attacks were carried out by local people, the perpetrators would have had some support and links with other groups besides umbrella ones like the Islamic State or even the Al-Qaeda. Security experts have long warned of the radicalisation of youths in the Maldives – an Indian Ocean atoll nation – situated close to Sri Lanka.

According to reports in Sri Lankan newspapers, 13 suspects had been taken into custody and were being probed for their connection to the NTJ. One of the reports – in Sri Lanka’s Daily Mirror – spoke of how one of the bombers with a suicide vest had lined up patiently at a restaurant at the Shangri La Hotel waiting to be served breakfast. He detonated his explosives just as he took his turn at the serving counter, the report said.

“It's unfortunate that the bombers managed to carry out the series of grisly attacks despite a nationwide alert in Sri Lanka since April 11. The alert was in response to a foreign intelligence tip-off that Thowheed Jama’ath was planning coordinated attacks," Indian security expert Brahma Chellany said in a Twitter post.

The Daily Mirror newspaper report said investigators had picked up “pamphlets and paraphernalia associated with extremist ideology" at the site of one of the blasts at the Shangri-la Hotel. Unidentified officials quoted by the paper said that the suspects were all a part of “one single ideology. They were all a part of a Radical Islamist group."

Meanwhile, Sri Lanka’s All Ceylon Jamiyyathul Ulama (ACJU) – an umbrella Muslim group -- has vehemently condemned the terrorist attack on churches and other places.

Issuing a statement, the president of the ACJU Mufti M.I.M Rizwe said, “this is a shameful and heinous act which no human being can tolerate for any reason. Though the attacks were carried out on a day holy to a particular religious community, it is a very sad day for all Sri Lankans."

Sri Lanka had seen relative peace for a decade with a three-decade long civil war coming to an end in May 2009. With Sunday’s blasts – targeting upmarket hotels besides churches – the target of the bombers seems to be the Sri Lankan economy as much as the ethnic fault lines in the country.