Finance Ministry P Chidambaram has expressed concern over the inflation in the primary articles category.In an interaction with students of Wharton Business School students in Philadelphia, Chidambaram said, "Even though the wholesale price index (WPI) based inflation rate has fallen to a near five-year low of 3.32% for the week ended September 8, inflation in one component of WPI - primary articles - touched 7.5%. This is worrying."Primary articles, comprising farm products, have a weight of 22% in the wholesale price index. According to official estimates released last week, although the overall rate of inflation fell, the index for primary items rose. Fruit prices had surged 17.7% a week earlier.Chidambaram said rising prices of primary food articles is a matter of concern. He said high food prices the world over and a demand-supply mismatch were the reasons behind high prices, which was beyond the influence of the monetary policy."Monetary policy will have effect only on core inflation, minus food. We are trying to mitigate this by importing wheat and pulses," he said.