MOSCOW (Reuters) - Russia did not seek an end to cooperation with OPEC or a sharp drop in oil prices, a senior Russian official told the TASS news agency, saying the Gulf nations are to blame for the crisis on global oil markets.The Organization of the Petroleum Exporting Countries (OPEC) and Russia this month failed to agree how their deal to cut oil output should work. With global oil demand slumping because of the coronavirus, OPEC wanted to deepen supply cuts but Moscow said it would agree..