“Our Embassy stands ready to provide assistance to any British nationals who may have been caught up in the attack,” says Hauge.

“We condemn all acts of terrorism. The UK stands shoulder to shoulder with Norway and all our international allies in the face of such atrocities. We are committed to work tirelessly with them to combat the threat from terrorism in all its forms,” he adds.

The incident, which also involves a mass shooting at an island near Oslo, has got people commemorating those who died, and wishing the injured speedy recovery across social networking sites such as Twitter.

Broadcaster Jeremy Vine wrote on his account “Is this Norway’s 9/11?” whilst Sarah Brown, former Prime Minister Gordon’s wife tweeted “thoughts go to Norwegians caught in horrific bomb blast (Norwegian Gov has been amazing supporter of maternal health before others listened).”

Experts interviewed by the British press have already pointed fingers to Islam extremist groups in revenge to the publication of Prophet Muhammad images.

“It may not be too dissimilar to the terrorist attack in Stockholm in December which saw a car bomb and secondary explosion shortly after in the downtown area,” says John Drake, senior risk consultant at London-based consultancy AKE on the Daily Mail website.

Other possible suspects include the Tamil Tigers, and al-Qaeda in response to Norway’s involvement in Afghanistan and Libya in recent years.

"This was not an attack on something more vulnerable such as a railway or a crowded shopping mall, this was an attack at the heart of the Norwegian body politic," says Sky News security editor Sam Kiley.

"It is clearly designed to send a very powerful political message."