India, July 21 -- International students studying in the United States, including thousands from India, are being advised by universities to return to the country before September 15, when a major overhaul of US immigration rules for student and exchange visas comes into force.

Several institutions, including Columbia University, have issued advisories to students currently abroad for summer or academic breaks, urging them to re-enter the US before the new regulations take effect.

In a notice to students, Columbia University said those holding F and J visas should return before classes begin to avoid potential complications under the revised immigration framework.

"This final rule has a 60-day implementation period. We recommend that a...