The Easter Sunday terror attacks in Sri Lanka that killed at least 359 people could have been prevented if key intelligence had been passed on correctly, the prime minister has admitted.
Eight Britons were among those who died in a series of blasts across the country targeting churches and hotels, with more than 500 people in total left injured.
Police have been investigating whether warnings of attacks were ignored or missed before the violence began, and now Ranil Wickremesinghe has confirmed there was a "breakdown of communication".
Speaking at a news conference on Tuesday, the prime minister said: "We could have prevented these attacks - or at least reduced the number of attacks."
He added that had vital information been correctly given to the relevant authorities, including himself, anti-terror measures could have kicked into gear "much faster".
Mr Wickremesinghe said an investigation had been opened into why the intelligence never reached him and that the heads of defence would be replaced "within the next 24 hours", with a complete restructuring of the police and security forces to follow "in the coming weeks".
His update came on what was a national day of mourning in Sri Lanka, with mass funerals and burials taking place in the capital Colombo and coastal city Negombo, which were among the locations struck.
He said investigators were making "good progress" in identifying who carried out the attacks, with Britain and the FBI among the foreign allies providing assistance.
Islamic State (IS) has claimed that its "fighters" were responsible, but has provided no evidence.
Mr Wickremesinghe said the bombers likely had "foreign links" and that the IS claim would be looked into, but the 40 suspects arrested so far are all Sri Lankan nationals.
"Some of the suspects are on the run," the prime minister added.
"Some of those suspects are armed and dangerous. There are still explosives and militants out there and the police are looking for them."
Footage has emerged of several masked bombers appearing to be preparing for their suicidal mission and pledging their allegiance to IS leader Abu Bakr Al-Baghdadi.
One of the men in the video, seen with his face uncovered, is Sri Lankan Islamist hate preacher Zahran Hashim.
Despite the claim by IS, the Sri Lankan defence ministry believes two domestic Islamist organisations are responsible for the attacks and that they were "retaliation" against the New Zealand mosque shootings in Christchurch.
But the office of New Zealand Prime Minister Jacinda Ardern has said they have not "seen any intelligence upon which such an assessment might be based".
As the investigation and widespread mourning continues, a nationwide daily curfew remains in place from 9pm and all social media is still banned in Sri Lanka in a bid to "ease tensions".
Police and military officers have also been granted emergency powers by the government to detain and interrogate suspects without court orders.
British Foreign Secretary Jeremy Hunt has sent specialists from the Metropolitan Police to help - and they will also be tasked with efforts to repatriate deceased UK nationals.
He told MPs in the House of Commons that the attacks were "primitive and vile attempts to sow division among people of different faiths" and that "we must deny the perpetrators the satisfaction of dividing us".
Mr Hunt also announced that the Bishop of Truro Philip Mounstephen had been asked to deliver an independent report into what more can be done to protect persecuted Christians around the world.
Following Mr Hunt's statement in parliament, Prime Minister Theresa May spoke to her Sri Lankan counterpart on the phone to express "her deepest condolences".
"Prime Minister May offered UK support to Sri Lanka, including sending UK counter-terrorism policing experts to provide assistance to authorities in the country," said a Downing Street spokesman.
"The leaders discussed the strong connection between the UK and Sri Lanka and the need to stand together in the fight against terrorism. Prime Minister Wickremesinghe expressed his gratitude for the UK's support."
Seven Britons who died in the attacks have been named , but it is not known whether there are any among the hundreds who suffered injuries in the various explosions.
In total, the bombing victims include more than 30 foreigners from at least 12 countries, including three children of Danish billionaire and ASOS shareholder Anders Holch Povlsen.
Unicef has said 45 children are among those who died.
:: Britons in Sri Lanka who need help are urged to call the high commission in Colombo on +94 11 5390639, while people in the UK worried about friends or family should call the foreign office on 020 7008 1500.