It will still be a few months before the total amount of old currency notes deposited with banks post-demonetisation is known since the RBI is doing a thorough physical verfication, Economic Affairs Secretary Shaktikanta Das said on Thursday.

"I expect the process of counting to get completed in the next few months. Counting capacity with the Reserve Bank of India is to take care of a normal situation when business is as usual. But here, suddenly 86 per cent of the currency in circulation got demonetised (on November 8 last)," Das told NDTV in an interview.

"Counting capacity has limitations, that's why it's taking time. I will not be able to spell out the deadline. Let's wait for the RBI to complete the process," he added.

Das is in Japan to attend the Asian Development Bank's 50th annual meeting.

He said the Finance Ministry, in discussion with the RBI, identified areas where double counting of notes might be happening because currency was moving from bank branches to their regional offices and then to the currency chests and the RBI.

"A decision was taken that it will be desirable to count the notes physically, to do a thorough physical verification of the notes received," he said.

Das said the task of counting of notes was enormous.

"The RBI has put all its counting machines to use. They are currently working overtime. The RBI is exploring possibility of getting additional counting facilities to speed up the process," he said.

Prime Minister Narendra Modi on November 8 last year announced demonetisation of Rs 500 and Rs 1,000 notes. The last date for depositing the scrapped currency notes in banks was December 30, 2016, though the window is still open till June 30 for Non-Resident Indians.