COPENHAGEN, Denmark -- Norwegian Prime Minister Erna Solberg said Tuesday the best way to honour the 77 people who died in terror attacks in her country three years ago is to "fight for openness, tolerance and diversity."

In a wreath-laying ceremony at the government headquarters, Solberg said "violent extremism can never be excused."

Far-right fanatic Anders Behring Breivik has confessed to the July 22, 2011, attacks in which he killed eight people in a bombing attack against the government headquarters and 69 others in a shooting spree at the left-wing Labor Party's youth camp on Utoya island.

In 2012, Breivik received a 21-year prison sentence that can be extended for as long as he's considered dangerous to society. Legal experts say that likely means he will be locked up for life.

Later in the day, Solberg, Labor Party head Jonas Gahr Stoere and members of the party's youth movement attended a second commemoration on Utoya, which sits in a lake 25 miles (40 kilometres) from Oslo.

"We can show this community's strength: we do not surrender to hatred and violence. We can show that there is another strength that is infinitely more powerful: compassion and solidarity," Stoere said before wreaths were put on the island's quay.