LONDON (Reuters) - OPEC and allies led by Russia have yet to find a consensus on oil output policy for 2021, after an initial round of talks on Sunday and ahead of crucial meetings on Monday and Tuesday, four OPEC+ sources told Reuters. OPEC+, a grouping comprising members of the of Organization of the Petroleum Exporting Countries, plus Russia and others, had been due to ease production cuts from January 2021, but a second coronavirus wave has reduced demand for fuel around the world. OPEC+ is now considering rolling over existing cuts of 7.7 million barrels per day, or around 8% of global demand, into the first months of 2021, sources have said. Preliminary consultations on Sunday between the key ministers, including from OPEC’s leader Saudi Arabia and Russia, had not reached a compromise on the duration of the rollover. Sources have said talks were now focusing on extending cuts by three to four months, or on a gradual increase in output. Ideas of deeper cuts or a six-month rollover were much less likely, the sources said. “There is no consensus as yet,” one of the four sources said. A second source said: “There are many different ideas on the table... Also, a gradual increase (in production).” The main meeting was expected to begin at 1300 GMT on Monday. Reporting by Rania El Gamal in Dubai, Alex Lawler and Ahmad Ghaddar in London and Olesya Astakhova and Vladimir Soldatkin in Moscow; Writing by Dmitry Zhdannikov; Editing by Alex Richardson Our Standards: The Thomson Reuters Trust Principles.