India's wholesale price deflation deepened in January dragged by falling prices in primary, fuel and power and manufactured goods, data showed on Monday, increasing the downward pressure on interest rates.

The annual WPI inflation rate fell to -0.39% in January from the December reading of 0.11%. The November print was revised to -0.17% from 0.0% prior.

The primary articles sector with a weight of 20.12% was down 1%, fuel and power with a weight of 14.91% was down while the 64.97% heavy manufactured goods prices eased 0.3%.

However, the January consumer price inflation data, released on 2 February with a new base year, had shown prices accelerating, so the rate guidance from overall prices data is not very clear.

Shares remained firm but the rupee continued to show weakness after the data.

The Reserve Bank of India had slashed the main repo rate by 25 basis points in an unscheduled meeting on 15 January but left the rate at 7.75% at the 3 February calendared review.

The RBI decision had boosted shares and rupee; the currency continued its upward movement another two weeks and hit a three-month high of 61.26 before reversing direction late last month.

On Monday, the rupee was at 62.26/US dollar, showing that the Indian unit has weakened more than 1.6% from its last month strong point. From Friday's closing, the rupee was down 0.3%.

At 7:15 GMT, the BSE Sensex 30, India's benchmark share index, was up 0.35% on the day at 29,210, after rising to a three week high of 29,322 earlier in the day.