By Jonathan Saul LONDON (Reuters) -London’s marine insurance market on Tuesday added the Ukrainian and Russian waters around the Black Sea and Sea of Azov to its list of areas deemed high risk as tensions persist in the region, a senior official said. Guidance from the Joint War Committee, which comprises syndicate members from the Lloyd’s Market Association (LMA) and representatives from the London insurance company market, is watched closely and influences underwriters’ considerations over insurance premiums. Following a buildup of Russian troops near Ukraine, Russia said on Tuesday some wer…