"At this dramatic time, I wish to pass on the profound sympathy of the entire French people for the Norwegian people," he said, responding to early reports of the bombing in the city centre and offering his condolences to the families of the victims.
French Foreign Minister Alain Juppé also condemned the attacks, describing them as "blind and savage acts of violence".
Norwegian intelligence did not consider the far-right as a serious threat to society and instead primarily feared an attack by Islamist extremists, according to an official report published this year.
With its forces involved in the NATO campaigns in both Afghanistan and Libya, Friday's tragic twin attacks prompted speculation that the country could have been paying a price for its participation in the Western alliance.
But after the arrest of a 32-year-old ethnic Norwegian, whom police have described as a "fundamentalist Christian" with political opinions that leaned "to the right", there has been a fundamental shift in focus.
In its annual threat assessment report released earlier this year, the Norwegian Police Security Service (PST) had detected a rise in far-right activity but said "the lack of strong leaders limits the growth of these groups."
"There was an increase in the activity of far-right extremist groups in 2010, and this activity is expected to continue in 2011," the PST said.
However "as in previous years, the far-right and far-left extremist communities will not represent a serious threat to Norwegian society in 2011," the report added.
The same report said there were indications of contacts between Norwegian far-right extremists and criminal groups, which could give far-right activists easier access to weapons and "thereby increase the potential for violence."
According to the TV2 channel, the arrested suspect possessed two weapons registered in his name. Other Norwegian media reported that the suspect, widely named as Anders Behring Breivik, was interested in hunting and computer games like World of Warcraft and Modern Warfare 2.
Norway's Prime Minister Jens Stoltenberg has refused to comment directly on the motives of the gunman who shot dead 84 people at a summer youth camp after seven other people were killed in a bomb attack in Oslo.
But in a press conference on Saturday, the prime minister denied that right-wing extremism was a particular problem for Norway.
"Compared to other countries I would not say we have a big problem with right-wing extremists in Norway," he said.
"We have had some groups, we have followed them before, and our police is aware that there are some right-wing extreme groups, or at least have been some groups of that kind in Norway.
"We will not speculate, we will wait for the investigation from the police before we say anything about this particular case but its part of the work of our police to follow this kind of right wing extreme group."
The PST report did however lay out fears of the "radicalisation" of some Islamists "who could present a direct threat to Norway in the year ahead."