The men, all in their early 20s, were on the roof of the overnight Gwalior-Udaipur Express on their way to sit the village accountancy exam in Bhilwara city, in the state of Rajasthan.

"We came to know about the incident when the train reached Bhilwara. Apart from the five deaths, four persons have been injured, two of them critically," divisional railway manager Sanjay Das said.

India's state-run railway system -- still the main form of long-distance travel despite fierce competition from private airlines -- carries 18.5 million people every day.

Roof-top travel is illegal but common as trains are often overloaded.

An accident early this month saw a speeding train ram into a stationary one in the southern state of Tamil Nadu, killing nine people and injuring 80.