The Federal Reserve said Tuesday it would launch a temporary lending facility that for the first time will allow foreign central banks to convert their holdings of Treasury securities into dollars, its latest bid to alleviate strains in global markets.

The program is designed to alleviate stresses in currency markets that had prompted more foreign central banks to sell their holdings of Treasurys. The Fed has been aggressively purchasing Treasury and mortgage securities to reduce market strains, and the latest move could reduce the supply of those securities hitting the market if foreign central banks can more easily exchange them for dollars.