India's foreign exchange reserves surged by $12.422 billion to a new all-time high of $729.328 billion during the week ended August 21, marking a sharp build-up in external reserves, official data released by the Reserve Bank of India showed on Friday.Foreign currency assets, the largest component of India's reserves, drove the latest increase, rising by $9.482 billion to $591.333 billion during the week.Gold reserves also contributed significantly, climbing by $2.801 billion to $114.218 billion.Special drawing rights (SDRs) rose by $112 million to $18.852 billion, while India's reserve position in the International Monetary Fund (IMF) increased by $26 million to $4.925 billion.The latest rise takes India's reserves $38.221 billion above their end-March level and $38.608 billion higher than a year earlier, according to RBI data.At $729.328 billion, the country's forex reserves have now surpassed the previous high of around $728 billion recorded earlier this year, strengthening India's external buffers against global financial and economic shocks.