New Delhi, Dec 16: State-run Indian Oil on Friday deferred the fortnightly revision of fuel prices without offering an explation although during the preceeding fortnight, global crude oil prices shot up well over $50 a barrel following a landmark agreement between major oil producers to cut output. Indian Oil Corp (IOC) Chairman B.Ashok told reporters here that “it is not compulsory” to change rates on a particular date. “We continue to review it and will take appropriate decision at the right time. Price revision is being done in a calibrated manner,” he said. State-run oil marketers, Bharat Petroleum and Hindustan Petroleum revise rates on the 1st and 16th of every month based on the average intertiol price in the previous fortnight. (IANS)