The country's foreign exchange reserves declined by USD 613.9 million to USD 393.12 billion in the week to December 14, on account of a fall in foreign currency assets, according to the RBI data.
In the previous week, the reserves had increased by USD 16.6 million to USD 393.734 billion.
In the reporting week, foreign currency assets, a major component of the overall reserves, dropped by USD 631.6 million to USD 367.865 billion.
Expressed in US dollars, foreign currency assets include the effect of appreciation or depreciation of non-US currencies such as the euro, pound and yen held in the reserves.
The reserves had touched a record high of USD 426.028 billion in the week to April 13, 2018. Since then, the forex kitty has been on a slide and is now down by over USD 31 billion.
Gold reserves rose by USD 37.2 million to USD 21.187 billion in the reporting week, the data showed.