Sri Lanka's police chief warned of potential suicide bombing plots on 'prominent churches' from Islamic extremists ten days before today's attacks which killed 207 people, according to reports.

Seven suspects have been arrested so far after the blasts hit high-end hotels and churches holding Easter services in Sri Lanka on Sunday, injuring as many as 500 people.

The cause was not immediately clear, and there have been no claims of responsibility so far, though the country remains deeply scarred by its 1983-2009 civil war, when Tamil rebels fought to create an independent homeland.

Recently a religious divide has taken hold in the country, which is 70 percent are Buddhist, 13 per cent Hindu, 10 per cent Muslim, and seven per cent Christian, according to the country's 2012 census.

Documents seen by news agency AFP reveal that Sri Lanka's police chief Pujuth Jayasundara issued an intelligence alert to top officers 10 days ago, warning that suicide bombers planned to hit 'prominent churches'.

Pictured: A Sri Lankan police commando enters a house suspected to be a hideout of militants in Colombo, April 21

Sri Lankan police stand at the site of an explosion at the luxury Shangri-La Hotel in Colombo on April 21, 2019

'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,' the alert said.

The NTJ is a radical Muslim group in Sri Lanka that was linked last year to the vandalisation of Buddhist statues.

The first blast was reported at St Anthony's Shrine, a well-known Catholic church in the capital Colombo.

A second deadly explosion was then confirmed at St Sebastian's, a church in the town of Negombo, north of the capital.

Soon after, police confirmed that a third church in the town of Batticaloa had been hit, along with three high-end hotels in the capital.

Hospital sources said British, Dutch and American citizens were among the dead, with Britons and Japanese among those injured in the attacks.

Security forces secure the area around the St. Anthony's Shrine after an explosion hit St Anthony's Church in Kochchikade, Colombo

The Easter Sunday attacks on churches and hotels in Sri Lanka are the latest flashpoint amid ongoing religious tensions in the island nation.

Sri Lanka has long been divided between the majority Sinhalese, who are overwhelmingly Buddhist, and minority Tamils who are Hindu, Muslim and Christian.

A Christian group said there had been 86 cases of discrimination, threats and violence against followers of Jesus last year, with another 26 so far this year.

The U.S. State Department warned in a 2018 report that Christians had been pressured to close places of worship after they were deemed 'unauthorised gatherings'.

The report also said Buddhist monks regularly tried to close down Christian and Muslim places of worship.

There have also been attacks on Muslims, with the government forced to declare a state of emergency amid a spate of anti-Muslim rioting.

Hard-line Buddhist groups accuse Muslims of forcing people to convert and destroying sacred Buddhist sites.

One radical Muslim group, the NTJ, has been linked to the vandalisation of Buddhist statues and has also reportedly plotted to attack Christian churches.