MOSCOW, July 23, 2011 (AFP) - Russian President Dmitry Medvedev on Saturday condemned the "monstrous" twin attacks on a youth camp and the government headquarters in Norway that killed at least 91 people.

"We condemn these monstrous crimes, for which there can be no justification, in the strongest terms," Medvedev said in a telegram of condolence to Norwegian Prime Minister Jens Stoltenberg.

"I am sure that the organisers and the perpetrators will be punished according to the full force of the law," he added in the telegram which was published on the Kremlin website.

In a separate message to King Harald V, Medvedev said that Russia, which shares an Arctic border with Norway, stood "in true solidarity in this hard hour" with its neighbour.

"I am convinced that those who organised and carried out these merciless and senseless crimes will be brought to responsibility and receive their deserved punishment," he said.

At least 84 people died in a shooting Friday at a summer school meeting organised by the ruling Labour Party on Utoeya, an island outside the capital, while seven were killed when a powerful bomb ripped through central Oslo, where the government headquarters are located, some two hours earlier.

Police said they were questioning a blond 32-year-old ethnic Norwegian they described as a Christian fundamentalist over both attacks.