The death toll from coordinated bomb explosions in Sri Lanka has risen to 310, as authorities continue their search for the perpetrators of the Easter Sunday attacks.

A local police spokesperson confirmed the revised figure on Tuesday afternoon (AEST).

It’s a significant jump from the previously reported figure of 290, with 500 more people wounded.

Overnight on Monday, Sri Lanka instituted a state of emergency, granting police wartime powers that allow them to detain and interrogate suspects without warrants. There’s also an overnight curfew and bans on social media.

Sri Lanka declares state of emergency from today following the deadly attacks. President Sirisena has issued the extraordinary gazette declaring it. pic.twitter.com/t9ID27HLM1

— Azzam Ameen (@AzzamAmeen) April 22, 2019

No group is yet to claim responsibility for the attacks, which targeted three Christian churches and three luxury hotels across the island nation.

However, police spokesman Ruwan Gunasekera said 40 people had been arrested. One of them is said to be a Syrian national.

The Sri Lankan government earlier admitted it failed to act on foreign intelligence suggesting Easter Sunday terrorist attacks on religious sites and tourist destinations were imminent.

Nerves remained frayed in Colombo after three bombs in a van near St Anthony’s Shrine, one of the attack sites, detonated as police tried to defuse them.

A vehicle bomb discovered & detonated by the disposal squad today in Colombo.Shockingly it was found near the St.Anthony's church where suicide attack took place yesterday.Impact of the controled blast was also very high. Metal pieces spread in tha large radius n houses damaged. pic.twitter.com/vDeD7fwxzu

— Pranay Upadhyaya (@JournoPranay) April 22, 2019

Sunday’s near-simultaneous attacks were the southern Asian nation’s worst day of bloodshed since its civil war fought by Tamil separatists concluded a decade ago.

Sri Lanka’s President Maithripala Sirisena declared Tuesday a national day of mourning. It was marked by a three-minute silence and the first mass burials for the victims.

Mourners have begun to farewell their loved ones who were killed in the Easter Sunday attacks. Photo: Getty

The Department of Foreign Affairs and Trade has issued a travel warning for Sri Lanka, advising Australians against going there.

Australians among the dead

Australian woman Manik Suriaaratchi and her 10-year-old daughter Alexendria were killed in the blast that tore through St Sebastian’s Catholic Church in Negombo.

Her distraught husband Sudesh Kolonne, who was outside the church following the Easter Sunday service, recalled his anguish to the ABC.

“I heard a huge noise and I jumped into the church and I saw that my wife and my daughter were on the floor,” Mr Kolonne said.

Australian father Sudesh Kolonne with wife Malik and daughter Alexandria, who were killed in Sri Lanka. Photo: Supplied

“I just saw my daughter on the floor and I tried to lift her up, [but] she was already dead. And [then] exactly the same… next my wife is there.”

The family moved back to Sri Lanka five years ago from Melbourne. A vigil was held in Melbourne for Ms Suriaaratchi and Alexendria on Monday night.

British doctor Sally Bradley and her retired firefighter husband Bill Harrop, who were living in Perth, were also among the dead.

The couple were staying in the Cinnamon Grand Hotel in Colombo, one of the high-end hotels targeted in the attacks.

Bill Harrop and Sally Bradley were killed in the Easter terror attacks in Sri Lanka. Photo: Supplied

Dr Bradley’s brother, former Manchester Withington MP Lord Keith Bradley, said the world had lost “a bright light in many people’s lives”.

“I have lost a sister, who was not only an inspiration to me, but someone that was respected and loved across Greater Manchester,” Lord Bradley said.

“The light may have been cruelly distinguished for no reason or justification, but she will always live in our hearts.”

Mr Harrop was commended for his role in the aftermath of the IRA Manchester bombings in 1996, in which he received a commendation for his leadership.

Danish billionaire’s children killed in blast

Three of Anders Holch Povlsen’s children, the chief executive of the parent company behind British fashion behemoth ASOS, also died in the suicide bombings, a spokesperson confirmed.

According to Forbes, Povlsen owns more than 1 per cent of all the land in Scotland.

Denmark’s richest man, who has an estimated net worth of $11 billion, was holidaying with his wife Anne Storm and their children when disaster struck, Danish media reported.

One of their daughters uploaded a holiday photo to Instagram five days ago. It has since become the site of condolence messages for the deceased children.

-with AAP