Sri Lanka's Easter Sunday bomb attacks were retaliation for a recent attack on mosques in New Zealand, a Sri Lankan official said on Tuesday.

Junior minister for defence Ruwan Wijewardene told parliament that two domestic Islamist groups were believed to be responsible.

"The initial investigation has revealed that this was in retaliation for the New Zealand mosque attack," he said.

"It was done by National Thawheed Jama'ut along with JMI," he said, referring to another local group, Jammiyathul Millathu Ibrahim.

Limited information is known about the terror group other than it being established last and affiliated with a group in Bangladesh of a similar name.

View photos At least 290 are now known to have died in a series of bomb blasts that tore through churches and luxury hotels in Sri Lanka. Source: Getty Images More

The death toll for the Easter Sunday bombings climbed to 310 on Tuesday, including two Australians identified as Manik Suriyaaratchi and her daughter Alexendria, 10.

The explosions, some of which officials said were suicide bomb attacks, led to an immediate clampdown, with the government declaring a curfew and blocking access to most major social media and messaging sites.

Prime minister Scott Morrison confirmed on Monday another two Australians - both of whom were dual citizens - were injured but were in a stable condition.

More than 500 people have been injured in the bomb blasts that ripped through three churches, three luxury hotels and a guesthouse.

The bombings were carried out by seven suicide bombers, a Sri Lankan government investigator said Monday.

View photos Security forces inspect St Anthony's Shrine after an explosion hit the church in Kochchikade, Colombo, Sri Lanka, during Easter Sunday service. Source: Chamila Karunarathne/Getty More

An analysis of the attackers’ body parts made clear that they were suicide bombers, said Ariyananda Welianga, a forensic crime investigator.

He said most attacks were by one bomber, with two at Colombo’s Shangri-La Hotel.

Meanwhile, Sri Lankan police investigating the bombings are examining reports that intelligence agencies had warnings of possible attacks, officials said Monday.

Bombings come after NZ mosque attacks

The attack followed a massacre in Christchurch on March 15 where at least one gunman opened fired at Masjid Al Noor and Linwood Masjid Mosques in Hagley Park.

Authorities announced a total of 50 people lost their lives and a further 39 people were injured in the attacks.

Australian citizen Brenton Harrison Tarrant, 28, was charged with 50 counts of murder and 39 counts of attempted murder.

He shot a live video for Facebook using a camera on his body, and posted a 74-page “manifesto” afterwards saying his motive was to avenge the deaths of thousands killed in attacks in Europe.

View photos Mourners pray at the graveside of a Christchurch shooting victim. Source: AP More

Tarrant, of Grafton, in the New South Wales Northern Rivers, live streamed himself performing the massacre as hundreds gathered for Friday morning prayer.

He described himself as “just an ordinary White man, 28 years old. Born in Australia to a working class, low income family”.

He said he had a regular childhood but had little interest in education and had recently worked as a “kebab removalist”.

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