LONDON, Dec 16 (Reuters) - Lloyd’s of London will phase out investments and ask its members to end underwriting in thermal coal power plants and mines, oil sands and new Arctic energy exploration activities, it said in its first sustainability report on Wednesday. The commercial insurance market has around 100 syndicate members, for which it also acts as regulator. It has previously said it left decisions over underwriting and investment strategy to its members. (Reporting by Carolyn Cohn, Editing by Franklin Paul)