Jens Stoltenberg hailed "the many heroes" and paid tribute to the victims of last week's attacks in Norway during a memorial ceremony Friday, dpa reported.
"The shots hit our youth, but affected a whole nation," Stoltenberg said in remarks at the ceremony organized by his ruling Labour Party.
The attacks left 76 dead, including 68 at a youth camp organized by the Labour Party on the island of Utoya, the scene of a shooting spree that followed a car bombing in Oslo.
"We will have to live with July 22 as ballast. It will be heavy, but together we will manage," the premier told party faithful.
As Stoltenberg addressed the gathering in Oslo, the funeral of an 18-year-old woman killed in the shootings at the Utoya island was underway in Nesodden, south of the capital.
Foreign Minister Gahr Store gave a funeral oration reminding how Bano Rashid came to Norway with her family from Iraq in 1996. She joined the youth wing of the Labour Party and was a candidate for the local council in Nesodden at the local elections in September.
A funeral was later held for a 19-year-old man who died at Utoya.