Norway's prime minister Jens Stoltenberg has led his country in mourning the murder of nearly 100 people in Friday's twin terrorist attacks. He told their families “you all should know that we’re crying with you”.

During a memorial service in Oslo to commemorate the dead, he said the “whole world” was grieving with Norway.

“Every single one of those we have lost is a tragedy in itself. Together the loss is a national tragedy. We are still struggling to understand the extent of this tragedy. Many of us knew somebody who is now gone. Even more know of someone. I knew several of them.”

Stoltenberg said he could not “understand or believe” the extent of the deaths but promised to respond with more humanity.

“In the middle of all this tragedy I am proud of living in a country that has managed to stand up on their feet in such a critical time… We are a small nation but we’re people. We are still horrified over what happened. But we will never give up our values.

“Our answer is more democracy, more openness, and more humanity but never naivety. No one has said it in nicer words than the girl from the local youth Labour party interviewed by CNN: ‘If one person can show so much hatred think how much love we all can show together.’

“Finally let me say to families all over the country that have lost one of their loved ones you have my and the whole nation’s deepest sympathy in your grieving.”

The Norwegian prime minister was commemorating those killed in a car bomb in Olso and in an attack in nearby island Utoya. Police said he fired at attendees of a political youth on the island for 90 minutes until surrendering.

The gunman, Anders Behring Breivik, has admitted carrying out the attacks and is in police custody.