The total reserves had risen USD 2.44 billion to USD 294.47 billion in the previous reporting week.
Foreign currency assets, a major component of the Forex reserves, were down by USD 485.6 million to USD 261.03 billion for the week ended September 21, RBI's weekly statistical supplement showed.
Foreign currency assets expressed in US dollar terms include the effect of appreciation or depreciation of the non-US currencies, such as the euro, pound and yen, held in the reserves, the apex bank said.
The gold reserves remained unchanged at USD 26.24 billion during the week, the apex bank said.
For the week under review, the special drawing rights (SDRs) were down by USD 11.2 million to USD 4.460 billion, while the country's reserve position with the IMF was also down USD 5.6 million to USD 2.243 billion, the apex bank data showed.