BEIJING, April 13 (Reuters) - China’s crude oil imports jumped 21% in March from a low base of comparison a year earlier as refiners ramped up operation amid robust fuel demand post-COVID-19, though purchases slowed ahead of the maintenance season. The world’s top crude oil buyer imported 49.66 million tonnes last month, equivalent to 11.69 million barrels per day (bpd), data from the General Administration of Customs showed on Tuesday. March imports were down from 11.73 million bpd last month. For the first quarter, arrivals totalled 139.23 million tonnes, or 11.29 million bpd. That compared to 10.2 million bpd over the same period a year earlier. (Reporting by Muyu Xu and Shivani Singh; Editing by Christopher Cushing)