The country's foreign exchange reserves declined by $862.2 million to $398.794 billion in the week to October 6 due to fall in foreign currency assets, RBI data showed.
In the previous week, the reserves had fallen by $2.590 billion to $399.656 billion. It had touched a lifetime high of $402.509 billion in the week to September 15.
The foreign currency assets (FCAs), a major component of the overall reserves, decreased by $1.391 billion to $373.795 billion, the data showed.
Expressed in US dollar terms, FCAs include the effect of appreciation or depreciation of non-US currencies such as the euro, the pound and the yen held in the reserves.
After remaining unchanged for past few weeks, gold reserves rose by $548.6 million to $21.240 billion.
The special drawing rights with the International Monetary Fund (IMF) declined by $7.9 million to $1.494 billion.
The country's reserve position with the IMF declined by $11.9 million to $2.264 billion, the apex bank said.