The 32-year-old Norwegian, Anders Behring Breivik, arrested on Saturday on suspicion of carrying out the twin attacks which killed over 90 people in the country, posted a small message on his Twitter account on the eve of the massacre.
His account has just one tweet, a quote from the philosopher John Stuart Mill: "One person with a belief is equal to the force of 100,000 who have only interests."
The message is dated July 17.
Anders also posted messages on Christian fundamentalist websites, Norwegian police said, but did not say which sites.
At least 80 people were killed on Friday in a shooting at a youth summer camp on Utoya Island near Oslo, police said.
A further seven people were killed in a bomb attack on a government building in Oslo few hours earlier. About 90 people were also injured in that attack.
Police said they had arrested a 32-year-old Norwegian who opened fire at the youth camp. He is also believed to have been behind the Oslo bombing.
The suspect is unlikely to be linked to any international terrorist organizations, police said.
Russian President and Prime Minister expressed their condolences to Norway. Muscovites are bringing flowers to the embassy of Norway from early morning.
Protection of Norwegian diplomats has been increased, a law enforcement source told RIA Novosti.
