A witness to Friday's shooting spree at a Norwegian island youth camp, which claimed at least 85 lives, has said he played dead to try and escape the gunman as he carried out the massacre.

Adrian Pracon was on tiny Utoeya island, outside Oslo, when the attack began just hours after a bombing rocked the capital.

The Oslo bombing killed at least seven. Prime Minister Jens Stoltenberg said the attacks were "like a nightmare".