As the rain fell, they laid wreathes and placed home-made posters calling for peace in the wake of the attacks which claimed more than 200 lives.

One message said: "Terrorism has no religion! Stand together."

Another said: "May all souls rest in peace."

The organiser, Sanji Gamaethige, said that Buddhists and Hindus had come as well as Christians who were the main victims of the attacks.

One of the mourners, Amila Badungodage, said, "We are against violence. We are against terrorism. We are all Sri Lankans."

Another, Jithmee Badungodage, said Sri Lanka was a multicultural country. "We came to remember and to give some blessing to those who died."

The grief and shock at the Easter Sunday bombings had been transmitted within the Sri Lankan community by social media through the day, culminating in the impromptu gathering in Yarralumla.

Mr Gamaethige said that several people had expressed the importance of coming together as a community, so he set up an event page where information could be shared. In less than an hour, 15 people had responded and it quickly gathered pace.

"There were concerned people exchanging messages back and forth on social media so I created a common platform so they could share their thoughts and express their grief," he said.

"There are about 3000 members of the Sri Lankan community in Canberra but with the holidays and many people away, social media can be a big help to get the message out."

He said that the gathering was an independent community gathering and there wasn't an expectation of any official presence from the High Commission.

Mr Gamaethige moved to Canberra from Sri Lanka in 2011. His family is from Kandy in the Central Province, but he had lived for 10 years in Colombo, which was the primary target of the multiple attacks on Sunday.

"This tragedy has personally not affected me but there are my friends and their families who are affected," he said.

"From the responses we have seen on social media, this tragedy has affected a broad cross-section of the Sri Lankan community, across all religious faiths."

He said it had been almost exactly 10 years since the previous war between government forces and the Tamil rebels ended.

"I have seen and heard and experienced the attacks previously from living in Colombo but this is something new and different; this is terrible for everyone," he said.

"In the war, most of the targets were economic [targets] like banks and oil refineries.

"This targeting of Christian churches and five-star hotels and foreigners; we haven't seen this before."

The resident monk at the Buddhist Vihara Temple in Kambah, Upali Thero, said the local Sri Lankan community was shocked to hear of the incidents and the temple turned to offering its Sunday evening prayers in support and blessings for those who were injured and in hospital.

"For 30 years we suffered with the war," the softly-spoken monk said.

"Everyone in Sri Lanka was finally enjoying the peace.

"But now, I'm not sure what has happened. This is a sad and uncertain time for us."

He said Sri Lanka's enormous support for the victims across all faiths was revealed when the call went out for immediate blood donations to assist hospitals with an overwhelming number of victims needing transfusions.

"All people from across the community responded; Muslim, Buddhist and Christian," he said.

"Everyone is wanting to support each other and to do what they can to help."

The Kambah temple is holding a special prayer ceremony for the victims of the bombings on Wednesday at 7pm, and an open invitation has been extended to everyone to attend.

"This is a time for people of all faiths to come together," Udali Thero said.

A spokesman for the High Commission in Canberra said no official statement would be issued at this time and referred to a written statement issued by the Sri Lankan Ministry of Foreign Affairs on Sunday.

A 24-hour emergency hotline to assist families of affected foreign nationals has been set up: +94 112323015.