Inflation remained at four month high of 5.64% during the week ended April 16 even as finance and petroleum ministries are yet to find ways to effect an imminent price hike in petro products.The point-to-point inflation based on the wholesale price index (WPI) rose by 0.16% from 5.48% in the previous week mainly due to costlier food and manufactured products even as minerals became cheaper. It was 4.68% a year-ago period.Observing that the recent surge in price levels was more due to base effect, finance minister P Chidambaram had said inflation was under control, but oil continues to be a concern, and promised steps to maintain price stability.The WPI was up 0.3% to 191.2 points due to an all-round increase in the indices of all the major commodity groups - primary, fuels and manufactured products despite international oil prices started sliding. It was 181 points in the previous year period.The government revised upwards inflation to 4.89% during the week ended February 19 as compared to the provisional estimate of 4.83% while WPI stood corrected at 188.9 points during the second week of February as against the provisional level of 188.8 points.