WASHINGTON, July 23, 2011 (AFP) - President Barack Obama condemned the "senseless" massacre of 92 people in twin attacks on Norway as he presented his condolences to Prime Minister Jens Stoltenberg, the White House said Saturday.

"The president offered any assistance the United States could provide to the Norwegian government in dealing with this horrible tragedy," the White House said in a statement.

"In this incredibly difficult time, the president reaffirmed the deep and longstanding friendship between the United States and Norway."

At least 85 people died in the island massacre on Friday and seven more were killed in an earlier car bomb explosion that ripped through government buildings in Oslo.

The toll could rise further as the search continued for four or five people still missing from the island, aided by a mini-submarine and Red Cross scuba divers.

While there was no official confirmation of the suspect's identity, he was widely named by the local media as Anders Behring Breivik, a self-described conservative Christian.

The White House said Obama called Stoltenberg to "express personally and on behalf of the American people his deepest condolences for the dozens of innocent Norwegians killed and injured in yesterday's senseless attacks in Oslo and Utoeya Island."

As harrowing testimony emerged from the summer camp where scores of youngsters were mowed down, Norway was struggling to understand how a country famed as a beacon of peace could experience such bloodshed on its soil.

"Never since the Second World War has our country been hit by a crime on this scale," Stoltenberg told journalists as police searched for more bodies on the idyllic Utoeya island.

"Many of those who have died were friends. I know their parents and it happened at a place where I spent a long time as a young person... It was a paradise of my youth that has now been turned into hell."