The 32-year-old Norwegian man arrested for gunning down children on a holiday island and detonating a car bomb in Oslo has been named locally as Anders Behring Breivik.

Described as 6ft tall and blond, he is reported to have arrived on the island of Utoyadressed as a police man and opened fire after beckoning several young people over in his native Norwegian tongue.

Reports suggest he was also seen loitering around the site of the bomb blast in Oslo two hours before the island incident.

More than 80 are believed to have been killed - in Oslo and on Utoya Island, 50 miles north of the capital, it was claimed.

Norwegian police said at least 80 were killed at Utoya alone and described the killings as of catastrophic dimensions andthe work of a madman.

It took investigators several hours to begin the realize the full scope of Fridays massacre, which followed an explosion in nearby Oslo that killed seven and that police say was set off by the same suspect.

The mass shootings are among the worst in history. With the blast outside the prime ministers office, they formed the deadliest day of terror in Western Europe since the 2004 Madrid train bombings killed 191.

A police official said the suspect appears to have acted alone in both attacks, and that it seems like that this is not linked to any international terrorist organizations at all.

This seems like a madmans work.

The Oslo bomb blast was outside a government office, while the island of Utoya is reportedly owned by the Norwegian Labour Party.

Teenagers on the Norwegian holiday island of Utoya had to swim for their lives and hide in trees when the gunman fired indiscriminately at them.

Around 700 had gathered on the island for a meeting of the youth wing of the ruling Labour party.

Witnesses said the man in police uniform who opened fire beckoned several young people over before shooting at them. He told them to come here.