Sri Lankan police have raided the headquarters of the hardline Islamist group founded by the suspected ringleader behind the Easter suicide bombings.
The raids came as Sunday mass was cancelled across the country because of fears of further attacks.
Armed police in the town of Kattankudy searched the headquarters of the National Thawheedh Jamaath (NTJ) and detained one man at the premises, a Reuters reporter at the scene said. Police did not comment.
On Saturday, the government banned the NTJ under new emergency laws. The authorities believe Zahran Hashim, the founder of NTJ, masterminded and was one of the nine suicide bombers in the attacks on Easter Sunday that killed 253 people.
Police sources told Reuters on Sunday night that Zahran’s father and two brothers were killed in a gun battle with security forces.
A relative identified the three men in a video circulating on social media calling for war against non-Muslims.
Islamic State claimed responsibility for the attacks.
Police suspect the bombings were carried out by two local Islamist groups, including the one established by Zahran. Around 10,000 soldiers have been deployed around the island as the authorities hunt for more suspects.
The Archbishop of Colombo Malcolm Ranjith, who had asked churches to suspend Sunday mass over security fears, delivered a televised special sermon from a chapel at his home.
The service was attended by President Maithripala Sirisena, Prime Minister Ranil Wickremesinghe and former president Mahinda Rajapaksa.
The archbishop said earlier this week that he had seen an internal security document warning of further attacks on churches.
“We cannot kill someone in the name of God … It is a great tragedy that happened,” the archbishop said in his sermon.
“We extend our hand of friendship and fraternity to all our brothers and sisters of whatever class, society or religion that differentiates us.”
The archbishop and political leaders then lit candles to commemorate the victims.
Most of those killed in the Easter Sunday attacks were Sri Lankans. The dead also included 40 foreigners, including Australian, British, US, Turkish, Indian, Chinese, Danish, Dutch and Portuguese nationals.
Police believe that radical Muslim preacher Zahran led the NTJ – or a splinter faction – to mount the attacks in Colombo as well as on a church in Batticaloa in the east.
The authorities have named the other group suspected of involvement as Jammiyathul Millathu Ibrahim.
Neither group were well known before the attacks but the government has come under heavy criticism for not heeding intelligence warnings of the bombings, including one from India’s spy service hours before the attacks.
On Friday, Sirisena said the government led by premier Wickremesinghe should take responsibility for the attacks and that prior information warning of attacks was not shared with him.
More than 100 people, including foreigners from Syria and Egypt, have been detained for questioning over the Easter attacks.