* More than 30 foreigners killed in attacks
* Police say many of the eight bombings were suicide attacks
* No immediate claims of responsibility
* Mosque and two Muslim-owned businesses attacked
* Condemnation pours in from around the world (Adds reports of attacks on mosque and Muslims)
By Ranga Sirilal and Shihar Aneez
COLOMBO, April 21 (Reuters) - More than 200 people were killed and at least 450 injured in bomb blasts that ripped through churches and luxury hotels in Sri Lanka on Easter Sunday, the first major attack on the Indian Ocean island since the end of a civil war 10 years ago.
The government declared a curfew in Colombo and blocked access to social media and messaging sites, including Facebook and WhatsApp. It was unclear when the curfew would be lifted.
But in a sign that the attacks on three churches and four hotels could lead to communal violence, police reported on Sunday night that there had been a petrol bomb attack on a mosque in the northwestern district of Puttalum and arson attacks on two shops owned by Muslims in the western district of Kalutara.
The government has acknowledged that it had "prior information" of attacks on churches involving a little known local Islamist group but didn't do enough about it.
Out of Sri Lanka's total population of around 22 million, 70 percent are Buddhist, 12.6 percent Hindu, 9.7 percent Muslim and 7.6 percent Christian, according to the country's 2012 census.
In February-March last year, there were a series of religious clashes between Sinhalese Buddhists and Muslims in the towns of Ampara and Kandy.
On Sunday afternoon, three police officers were killed during a security forces raid on a house in the Sri Lankan capital several hours after the attacks, many of which officials said were suicide bomb explosions. Police reported an explosion at the house.
Thirteen arrests have been made, all of whom are Sri Lankans, police said.
"Altogether, we have information of 207 dead from all hospitals. According to the information as of now we have 450 injured people admitted to hospitals," police spokesman Ruwan Gunasekera told reporters.
Government officials said that 32 foreigners were killed and 30 injured in the explosions that tore through congregations and gatherings in hotels in Colombo, Negombo and Batticaloa.
They included five British people, two of whom had dual U.S. citizenship, and three Indians, according to officials in those countries.
Also among the fatalities were three people from Denmark, two from Turkey, and one from Portugal, Sri Lankan officials said. There were also Chinese and Dutch among the dead, according to media reports.
U.S. Secretary of State Mike Pompeo said U.S. nationals were among those killed, but did not give details.
There were no immediate claims of responsibility for the attacks in a country which was at war for decades with Tamil separatists until 2009, a time when bomb blasts in the capital were common.
Prime Minister Ranil Wickremsinghe acknowledged that the government had some "prior information of the attack", though ministers were not told.
He said there wasn't an adequate response and there needed to be an inquiry into how the information was used.
He also said the government needs to look at the international links of a local militant group.
Agence France Presse reported that it had seen documents showing 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". He cited a foreign intelligence service as reporting that a little-known Islamist group was involved.
A Sri Lanka police spokesman said he was not aware of the intelligence report.
Dozens were killed in one of the blasts at St. Sebastian's Gothic-style Catholic church in Katuwapitiya, north of Colombo. Gunasekera said the police suspected a suicide attack there. Pictures from the site showed bodies on the ground, blood on the church pews and a destroyed roof.
Local media reported 25 people were also killed in an attack on an evangelical church in Batticaloa in Eastern Province.
The hotels hit in Colombo were the Shangri-La, the Kingsbury, the Cinnamon Grand and the Tropical Inn near the national zoo. There was no word on casualties in the hotels, but a witness told local TV he saw some body parts, including a severed head, lying on the ground beside the Tropical Inn.
The first six explosions were all reported within a short period in the morning just as church services were starting.
One of the explosions was at St. Anthony's Shrine, a Catholic church in Kochcikade, Colombo, a tourist landmark.
The explosion at the Tropical Inn happened later and there was an eighth explosion at the house that was the subject of the police raid in Colombo.
"I strongly condemn the cowardly attacks on our people today. I call upon all Sri Lankans during this tragic time to remain united and strong," said Sri Lanka's prime minister in a Tweet.
"Please avoid propagating unverified reports and speculation. The government is taking immediate steps to contain this situation."
President Maithripala Sirisena said he had ordered the police special task force and military to investigate who was behind the attacks and their agenda.
The military was deployed, a military spokesman said, and security stepped up at Colombo's international airport. Schools, universities and the Colombo Stock Exchange will be closed on Monday as the island state tries to recover from the attacks.
The Christian community had already felt under pressure in Sri Lanka in recent years.
Last year, there were 86 verified incidents of discrimination, threats and violence against Christians, according to the National Christian Evangelical Alliance of Sri Lanka (NCEASL), which represents more than 200 churches and other Christian organisations.
This year, the NCEASL recorded 26 such incidents, including one in which Buddhist monks allegedly attempted to disrupt a Sunday worship service, with the last one reported on March 25.
The heads of major governments condemned the attacks.
U.S. President Donald Trump said America offered "heartfelt condolences" to the Sri Lankan people and stood ready to help, Indian Prime Minister Narendra Modi said there was "no place for such barbarism in our region", and Turkish President Tayyip Erdogan said the bombings were "an assault on all of humanity".
Pope Francis, addressing people in St. Peter's Square, said: "I wish to express my affectionate closeness to the Christian community, hit while it was gathered in prayer, and to all the victims of such cruel violence."
Christians celebrate the resurrection of Jesus Christ on Easter Day after his death on the cross.
Prime Minister Jacinda Ardern of New Zealand, where a gunman shot 50 people dead in two mosques last month, said in a statement: "Collectively we must find the will and the answers to end such violence."
Writing by John Chambers and Martin Howell; Editing by Raju Gopalakrishnan, William Maclean