British nationals living or visiting in Norway have been urged to stay indoors in the wake of the worst atrocity in the country's post-war history.

Foreign Office travel advice warned there was a high threat from terrorism and called on British nationals to take extra care.

In a statement on its website, the Foreign Office said: 'On the afternoon of 22 July there was an explosion in the centre of Oslo resulting in a number of casualties. This was followed by a further attack at a youth camp on Utoya Island, 40km west of Oslo.'

'We recommend that British nationals stay indoors for the time being. British nationals are advised to exercise caution, monitor local media reporting and follow advice given by the emergency services.'

The Foreign Office said that although it had reviewed it, its overall level of travel advice had not changed and there were no travel restrictions in place in Norway.

About 250,000 British tourists visit the country every year.

David Cameron has expressed outrage at horrific attacks in Norway that have left more than 80 people dead.

The Prime Minister pledged Britain's help in overcoming the 'evil' behind a huge bomb in Oslo and mass shootings at a youth camp on an island near the capital, where scores of people were gunned down.

The suspected gunman, who was arrested during the shooting rampage, is also believed to have carried out a devastating bomb attack in Oslo earlier in the day.

A police official said the attacks did not appear to be linked to Islamic terrorism.

Do you know any Norfolk or Suffolk people in Oslo at the moment? Contact the newsdesk on 01603 772443.