The Reserve Bank of India (RBI) on Tuesday announced the hike in foreign portfolio investors' (FPIs) investment limits in central government securities (G-Secs) by Rs 6,400 crore beginning January 1, taking the total limit to Rs 2.56 lakh crore. Of this, the general-category FPIs will get an additional limit of Rs 1,600 crore while long term FPIs will get an additional limit of Rs 4,800 crore. At the same time, the central bank has also hiked the FPI investment limits in state development loans (SDLs) by Rs 5,800 crore taking the total limit to Rs 45,100 crore. Of this, a limit of Rs 1,500 crore has been reserved for general category FPIs while long term FPIs will get an additional limit of Rs 4,300 crore. Foreign investors have been upbeat on central government securities. General category FPIs have almost exhausted the permitted investment limit of Rs 1.89 lakh crore in G-Secs. However, investor interest has remained dull in SDLs. In the general category, FPIs have utilised just 17.11% of the allotted quota of Rs 30,000 crore while the long-term FPI quota of Rs 9,300 crore still remains completely unutilised. The latest Mint Street memo\u2014written by RBI officials but not necessarily interpreted as the RBI's official views\u2014hints at the possibility of reviewing implicit and explicit guarantees and regulatory treatment of state government bonds in order to allow the market to differentiate between them.