New Delhi - Rising prices of metals and food items have pushed India's inflation rate to 6.68 per cent, the highest rate in the past 12 months, government data showed Friday. The inflation rate, based on the wholesale price-based index, reached 6.68 per cent for the week ending March 15, compared to 5.92 per cent the previous week, according to data released by the federal Reserve Bank of India (RBI).…