"The increase is on account of addition of 8.46 tonne of gold during the year," the report said.
Last time the apex bank purchased gold was in November 2009, when it had bought 200 tonne of yellow metal from the International Monetary Fund (IMF).
Of 566.23 tonne of gold reserves, 292.30 tonne is held as backing for notes and is shown as an asset of the Issue Department, and the balance 273.93 tonne is treated as an asset of the Banking Department.
The value of gold held as asset of Banking Department rose by 11.12 per cent to Rs 696.74 billion as on June 30, 2018, from Rs 627.02 billion as on June 30, 2017.
This increase was primarily on account of depreciation of rupee as against the dollar and the addition of 8.44 tonne of gold during the year, RBI report said.