Cameron said he 'was outraged to hear about the explosion in Oslo and attack in Utoya' [Reuters]

International leaders have condemned twin attacks in Norway that have left 91 people dead.

At least 84 people were killed in a shooting spree on Utoya island, nearly two hours after a bomb blast killed seven people in the capital of Oslo on Friday.

Hillary Clinton, the US secretary of state, said: "The United States strongly condemns today's attacks in Oslo and Utoya Island. 

"We stand with the people of Norway in this moment of sorrow and offer our deepest sympathies to the families and loved ones of those injured and killed."

David Cameron, the British prime minister, said he "was outraged to hear about the explosion in Oslo and attack in Utoya".

Cameron said: "These attacks are a stark reminder of the threat we all face from terrorism.

"I have called Prime Minister Stoltenberg this evening to express my sincere condolences and to let him know that our thoughts are with the Norwegian people at this tragic time."

In Berlin, Angela Merkel, the German chancellor, said she was "horrified". 

Nicholas Sarkozy, the French president, offered the "profound sympathy of the entire French people for the Norwegian people".

Julia Gillard, the Australian prime minister expressed her condolences and said: "From the tales that are now being told by survivors, it's clear that many have lived through absolute nightmares."

Marty Natalegawa, the Indonesian Foreign Minister, said: "I think all of us are shocked and dismayed by what has happened and I am sure all of us would want to express our deepest condolences and sympathy to the people and government of Norway."

Anders Fogh Rasmussen, Nato's secretary-general, said: "On behalf of Nato, I condemn in the strongest possible terms the heinous acts of violence in Norway.

"I would like to convey my sincere condolences to the Norwegian government, the Norwegian people and the families and loved ones of all those who suffered in these cruel and cowardly acts."

Ban Ki-moon, the UN secretary-general, voiced his shock after the bomb blast hit Oslo.

Condemning the violence, he said: "The UN stands together with the people of Norway at this terrible moment."

Speaking at a news conference on Saturday, Jens Stoltenberg, the Norwegian prime minister, described the attacks as a "national tragedy".

Stoltenberg said: "We appreciate the very strong international support we have received.

"Countries have expressed the will to help with intelligence and how we can exchange information to assist us in the ongoing investigation."