However, no casualty was reported.
The smoke from the 3rd AC bogie was noticed when the superfast train was near Tuni station, about 120km from here in Andhra Pradesh's East Godavari distract, they said.
Some train passengers and the guard noticed the smoke and authorities at Tuni were immediately alerted, Rajahmundry Station Master B V Sastry told PTI.
On inspection, the authorities found that a conveyor belt had caught fire due to overheating. The damaged belt was replaced and the train left for on its onward journey after around 30-minute halt, during which other coaches were also inspected thoroughly, he said.
The incident comes in the backdrop of a spate of cases of train fires in the last few months in which scores of people have been killed.