A series of explosions ripped through luxury hotels and churches holding Easter services, killing at least 207 people and injuring 450 more.

Islamic State may be preparing to take credit for the Easter Sunday suicide bombings in Sri Lanka that have left at least 290 dead and around 500 injured, a terrorism expert has warned.

No group has officially claimed responsibility for the blasts, which ripped through three churches, four luxury hotels and a unit block in Colombo. Scores more died in attacks in Negombo and Kochchikade, north of the capital, and Batticaloa in the island nation’s east.

SITE Intelligence Group director Rita Katz says IS supporters have boasted on social media Colombo was revenge for the Christchurch mosque massacre and the US-backed military campaign in Syria.

Australian born Brenton Tarrant is facing 50 counts of murder and 39 counts of attempted murder after opening fire on two Christchurch mosques in New Zealand’s worst terror attack.

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1) Hundreds killed and hundreds more wounded in Easter blasts at #SriLanka churches. While no group has yet claimed responsibility, targeting Christians is a staple of #ISIS attack directives (not to mention past attacks in places like Egypt). pic.twitter.com/USGwiCnw1v — Rita Katz (@Rita_Katz) April 21, 2019

8) At this point, #ISIS channels—posting rampantly, praying “may Allah accept” the attackers, celebrating casualties, etc.—are clearly paving way for ISIS to claim responsibility. While such a claim may frame the op as revenge for #NewZealand, this was likely planned long before. pic.twitter.com/j4dSfs7wWB — Rita Katz (@Rita_Katz) April 21, 2019

Ms Katz said IS media channels were “posting rampantly” about the explosions and praying “may Allah accept” the attackers, indicating the group may be planning to claim responsibility.

“While such a claim may frame the op as revenge for New Zealand, this was likely planned long before,” she said.

An infographic gloating about the death toll has also been disseminated on social media by IS supporters.

The death toll from the eight blasts is expected to soar past 300, with hundreds more injured, many of them critically.

Around 30 foreigners are among the dead, including five British nationals — two of whom held dual US citizenship. The others came from China, Denmark, The Netherlands, India, Portugal and Turkey.

It has not yet been established whether any Australians are among the casualties.

Authorities have arrested 13 people over the attacks, describing those in custody only as “religious extremists”.

Ms Katz said the attacks bore chilling similarities to the bombing of a Roman Catholic cathedral on the island of Jolo in the southern Philippines in January.

IS claimed responsibility for twin blasts, which killed 20 worshippers and wounded scores more.

Sri Lankan fighters have been rising in the ranks of IS, and the country would have been “easily accessible” for its supporters in the region, Ms Katz said.

In 2016, the Sri Lankan Justice Minister Wijeyadasa Rajapakshe warned 32 people from prominent Muslim families had slipped out of the country to fight for IS in Syria in a surge of local support for the terror group.

“They are not from ordinary families, these people are from the families which are considered as well-educated and elite,” Minister Rajapakshe said, according to Reuters.

He said the Government had also received intelligence foreigners were entering Sri Lanka to spread what he called Islamic “extremism”.

The Colombo attacks come just weeks after IS launched a massive global military campaign dubbed the “Revenge Invasion” as payback for the loss of territory in Syria.

It has emerged Sri Lanka’s police chief Pujuth Jayasundara warned suicide bombers were planning to hit “prominent churches” 10 days before yesterday’s attack.

“A foreign intelligence agency has reported that the NTJ (National Thowheeth Jama’ath) is planning to carry out suicide attacks targeting prominent churches as well as the Indian high commission in Colombo” he said.

The NTJ is a radical Muslim group that was linked to the destruction of Buddhist statues last year.

Clashes between Sinhalese Buddhist and Muslim communities have escalated in recent months, with some hard-line Buddhist groups accusing Muslims of forcing people to convert to Islam.

But Muslims have also been targeted. In 2018, mobs of Buddhists descended on small towns in the hills of central Sri Lanka, attacking mosques and Muslim-owned shops.

Viral misinformation and calls for anti-Muslim violence, circulating largely on Facebook, were blamed for the riots and lynchings that followed.

In response, the Government cut off the population’s access to social media, a strategy it also adopted in the wake of yesterday’s terror attacks.

Economy Minister Harsha de Silva said yesterday the latest ban was temporary and access would be allowed again “once investigations have concluded”.

Only about 6 per cent of majority-Buddhist Sri Lanka is Catholic, but the religion is seen as a unifying force because it includes people from both the Tamil and majority Sinhalese ethnic groups.

Last year, there were 86 verified incidents of discrimination, threats and violence against Christians, according to the National Christian Evangelical Alliance of Sri Lanka.

The Colombo bombings are the worst violence in Sri Lanka since the country’s bloody civil war ended a decade ago.