Mumbai, Sep 15: The country's forex reserves surged by USD 2.604 billion to reach an all-time high of USD 400.726 billion in the week ended September 8 on account of rise in foreign currency assets, RBI data showed on Friday. In the previous week, the reserves had increased by USD 3.572 billion to USD 398.122 billion. The foreign currency assets (FCAs), a major component of the overall reserves, increased by USD 2.568 billion to USD 376.209 billion for the reporting week, according to data by the Reserve Bank of India (RBI). Expressed in US dollar terms, FCAs include the effect of appreciation or depreciation of non-US dollar currencies, such as the euro, the pound and the yen held in the reserves. The gold reserves remained unchanged at USD 20.691 billion. The special drawing rights with the International Monetary Fund (IMF) increased by USD 14.2 million to USD 1.520 billion, the apex bank said. The country's reserve position with the IMF also increased by USD 21.4 million to USD 2.304 billion, it said.