New Delhi, July 16 - India's annual rate of inflation rose marginally to minus 1.21 percent for the week ended July 4, from minus 1.55 percent the week before, according to official data released here Thursday.

India's annual rate of inflation turned negative for the week ended June 6 for the first time since the new wholesale price index (WPI) series started in 1995.

The inflation rate had last turned negative in 1977. Negative inflation implies that the average wholesale price level was lower during a given week, than it was in the corresponding week a year ago.

The price index for primary articles remained unchanged at its previous week level of 258.5 (provisional), while that for manufactured products rose by 0.2 percent.

However, the price index for fuel and power rose steeply by 3.1 percent to 338.2 (provisional), from 327.9 (provisional) for the previous week due to higher prices of naphtha (15 percent), furnace oil (11 percent), petrol (10 percent), high speed diesel oil (7 percent) and bitumen (2 percent).

The final data for the week ended May 9 showed that the revised annual inflation rate actually stood at 1.56 percent.