A federal judge on Thursday said Citigroup Inc (C.N) cannot process interest payments by Argentina on some bonds issued under that country’s law, a defeat for the cash-strapped nation as it attempts to re-enter international debt markets. U.S. District Judge Thomas Griesa in Manhattan said letting Citigroup process the payments on so-called dollar-denominated exchange bonds would violate a requirement that Argentina treat bondholders equally. Griesa’s decision upheld his order on July 28 that blocked Citigroup from making the payments on an estimated $2.3 billion of bonds.