Tjostolv Moland, one of two Norwegian citizens imprisoned in Congo since 2009 on murder charges, has died in prison.
British-Norwegian citizen Joshua French, 31, who was imprisoned alongside the 32-year-old, is upset but in good health, lawyer Hans Marius Graasvold said. The cause of Moland's death was not immediately clear.
The two former Norwegian soldiers were convicted of espionage and the murder of a local driver and sentenced to death. They have consistently denied the charges against them, and the Norwegian authorities have tried to have them transferred to serve their sentences in Norway.
Norway's foreign minister, Espen Barth Eide, said Moland was found dead in his cell on Sunday morning and that his family had been informed.
"More than anything our thoughts now are with them in this very difficult situation," Eide said, adding that the government had been concerned about French and Moland for a long time.
Norway and Britain have worked together to find a solution for French and Moland, and Eide said he has kept Britain's foreign secretary, William Hague, informed.