An invitation has been issued to artists around the world to submit proposals for memorials to mark the Norwegian terror attacks of two years ago that claimed 77 lives.

The Norwegian government, which has earmarked 17m Norwegian kroner (£1.8m) for the project, said it had opened it up to as wide a range of international participants as possible as an expression of the spirit it hoped the final memorials would embody.

"We are looking for ideas from everyone from visual artists, architects, sculptors, and landscape architects, from anywhere in the world, to produce memorial sites of relevance for the victims' families and the Norwegian public as a whole," said Jorn Mortensen, of the government's public arts agency Koro.

Two memorials are planned, one in the government quarter in Oslo where eight people were killed and 209 injured on 22 July 2011 when a car bomb planted by Anders Behring Breivik exploded, and the other in the Hole district within sight of Utøya island where two hours later Breivik shot dead 69 people and injured 110.

Initially a temporary memorial will be built in Oslo because of the extensive reconstruction work that is going on in the government quarter to increase its safety in the light of the attacks. It will later be replaced by a permanent monument.

Mari Aaby West, 27, one of hundreds of members of the youth division of the Norwegian Labour party (AUF) who witnessed the attacks as she participated in a summer camp on Utøya island, said it was important for Norwegians, especially those who lost family and friends, to have sites of remembrance to visit.

"It's necessary to create places where people can gather and grieve and reflect on what happened, and of course to remember those who were killed," she said. "For many families it's still too difficult to go to Utøya and so it will be important for them to have an alternative place they can meet and remember as well as to learn something from it."

Aaby West will represent the AUF on the jury that will select eight projects from the initial submissions. The winners are expected to be announced in spring 2014. The AUF also plans to erect a monument of its own on Utøya.

Artists will be invited to draw inspiration from the national archive's collection of items that were gathered around the time of the attacks and during Breivik's trial last summer, including letters and drawings left at the massacre sites, Twitter and Facebook messages and even the compost that was created out of the millions of flowers laid as tributes.

"If the artists truly involve themselves with what happened, it's possible they will be able to come up with a memorial that will speak to as many people as possible," Aaby West said.

The public has also been consulted in a nationwide survey. While some have said it is still too soon for a memorial, Mortenson said: "The trial made quite a heavy impact in helping Norwegian society deal with the trauma of the incident, and to secure the relevance of the memorial it feels right to do it now rather than reigniting the trauma again in years to come."

• This article was amended on 16 July 2013 to correct a conversion of Norwegian kroner to pounds. This article was further amended on 18 July 2013 to change singular krone to plural kroner.