Food inflation surged back into double-digit territory at 12.13 per cent for the week ended December 11 as the prices of vegetables, particularly onions, rose for the third consecutive week. Food inflation registered a sharp increase during the week under review from 9.46 per cent in the previous week to enter double digits for the first time since November 13, when it stood at 10.15 per cent.On an annual basis, onions became costlier by 33.48 per cent, whereas on a week-on-week basis, the increase was 4.56 per cent. While fruits and milk became 20.15 per cent and 17.83 per cent more expensive year-on-year, vegetables became 15.54 per cent dearer.RBI Deputy Governor Subir Gokarn had yesterday hinted that more tightening monetary measures were likely to be taken by the apex bank at its next policy review, as headline inflation is not easing as fast as the apex bank would like.