Kaj-Erik Relander, the former chief executive of Sonera and a London-based partner of Accel Partners, the venture capital firm, has flown to Finland to help police investigations into stock market manipulation.

Relander made the journey after proceedings for his arrest were started by Finnish police earlier this week. Sonera said in a note to the stock exchange: "Sonera Corporation has learned that The National Bureau of Investigation has arrested Kaj-Erik Relander. The reason for the arrest is that he is suspected on reasonable grounds for gross violation of secrecy of communications."