LONDON, April 15 (Reuters) - U.S. sanctions announced on Thursday on newly-issued Russian government debt could see the bonds excluded from JPMorgan’s influential emerging market local-currency GBI-EM investment index, the bank said. “Economic sanctions which impact the replicability of the J.P. Morgan fixed income indices will result in an Index Watch (observation period) followed by potential rebalance actions such as exclusion of the sanctioned bonds/issuers from the benchmark,” JPMorgan said. That said, JPMorgan added there would be no immediate impact on the existing EMBI or GBI-EM series composition. “Existing index composition, i.e. rouble-denominated Russia government bonds (OFZs) in the GBI-EM series, dollar- and euro-denominated Russia sovereign and quasi-sovereign bonds in the EMBI and Euro EMBIG series, will remain eligible at this time provided these securities satisfy all other index eligibility criteria.”