Police have raided the headquarters of the banned group NTJ as sources said the father and brothers of the suspected mastermind of the Easter bombings were killed on Friday.

Authorities entered the main mosque used by National Towheed Jamaat on Sunday, the day after it was proscribed as a terror group.

Police then left, locking up the mosque in Kattankudy in eastern Sri Lanka, just before afternoon prayers were to start.

Image: A police officer inspects debris at the site of the gun battle

Meanwhile, four sources told Reuters that Zainee Hashim, Rilwan Hashim and their father Mohamed Hashim, were among 15 killed in a fierce gun battle about 23 miles (37km) away on Sri Lanka's east coast on Friday night.

Mohamed Hashim Mohamed Zahran, the suspected ringleader of the bombings that killed over 250 people on Easter Sunday, remains at large.


Image: A Sri Lankan soldier stands guard at a barricade near St Anthony's Shrine in Colombo

The three dead men were in a video circulating for some time on social media in which they urged their followers to kill all non believers, police sources said.

Islamic State's Amaq news agency gave the names of three who died in the shootout as Abu Hammad, Abu Sufyan and Abu al Qa'qa.

It said they opened fire with automatic weapons and "after exhausting their ammunition" blew themselves up.

Six children and three women were among the 15 who died in the safe house in Sainthamaruthu, Ampara district.

A girl and a woman, who have been identified as Zahran's wife and daughter, are understood to have been critically injured.

Suicide bomber checks into hotel before blast

IS falsely claimed 17 "disbelievers" were killed by their militants in the attack. A Reuters source said two policemen were slightly injured.

Image: A Sri Lankan soldier stands guard near St Sebastian's Church in Negombo

Security forces were said to have recovered explosives, detonators, "suicide kits", military uniforms and IS group flags during the raids.

Bomb-making materials, dozens of sticks of gelignite, thousands of ball bearings and IS banners and uniforms were found in a separate house in the same area, the military said.

NTJ and another group, Jamathei Millathu Ibrahim, or JMI, were banned by presidential decree soon after the blasts.

Zahran's driver has also been held in a separate raid, police said.

He appeared in a different video released by IS days after the Easter bombing under a black IS flag.

He and a group of seven other men declared their loyalty to IS leader Abu Bakr al Baghdadi.

Earlier, many Sri Lanka's Catholics celebrated Sunday mass in their homes as churches remain shut over fears of further militant attacks.

Image: Sri Lankans pray in the street near St Anthony's Shrine

Others took part in memorial masses in the street outside closed places of worship.

Members of the public watched a televised broadcast of the service from their homes, a week after suicide bombers had hit three churches and three international hotels and tried to target another guesthouse.

Cardinal Malcolm Randith, the archbishop of Colombo, delivered a homily from a small chapel at his residence.

"This is a time our hearts are tested by the great destruction that took place last Sunday," he said.

"This is a time questions such as, does God truly love us, does He have compassion towards us, can arise in human hearts."

Image: A woman sits by a grave after mass burials near St Sebastian church in Negombo

Sri Lanka's president and prime minister attended the mass in a show of attempted unity after a week in which the country's political fractures have been exposed.

Mass burials of the victims continued over the weekend after the attacks that left 40 foreigners, including eight Britons dead.

Image: Sunday Mass was televised to the nation from the archbishop's residence

On Friday, the country's president said police were searching for 140 suspects thought to have links with the Islamic State terrorist group, which has claimed responsibility for the bombings.

On Sunday, Sky News reporter Neville Lazarus, who is in the capital Colombo, said 106 of those suspects have been arrested and are being questioned.