OSLO - A Norwegian man suspected by Russia of espionage has admitted to being a courier for Norway's military intelligence, his Norwegian lawyer said on Sunday.Frode Berg, a retired former guard on the Norwegian-Russian border, has been detained since his arrest in Moscow last December, but had little knowledge of the operation he took part in, Berg's lawyer Brynjulf Risnes told daily Dagbladet and broadcaster NRK."We're quite certain that what he did in Russia was partly to carry out tasks for Norwegian intelligence," Risnes told NRK, while adding that his client felt he had been let down by those who had sent him."He did not understand the extent of this or how dangerous it could become," Risnes said.Dagbladet reported that on his arrest Berg was carrying 3,000 euros ($3,686) in cash, and that police suspected the money would be mailed to a Russian man to pay for information about the country's nuclear submarine fleet.Berg posted a picture of a snow-covered Red Square on his Facebook profile page early on Dec. 5, the day of his arrest, with the message "Christmas Time in Moscow!."The maximum penalty for espionage in Russia is 20 years in prison, while the minimum sentence is 10 years, Risnes told Reuters last year.Norway's military declined to comment. The foreign ministry said it was providing consular services.