Monetary policy action taken by Reserve Bank of India (RBI) should start to show its impact on inflation over the next 6 to 12 months, a central bank deputy governor has said.

"One strong criticism of the Reserve Bank's approach has been that it has been "too little, too late". I would submit that the test of this is yet to come," Subir Gokarn said in a article which was published on the bank's website on Thursday.

"It is well-known that monetary policy acts with a lag."

The Reserve Bank of India has raised rates by 25 basis points each in March, April and early July, and followed this with a more forceful hike late last month.