Officials were investigating whether Maoist rebels had tampered with the track, after eight coaches and the engine of the Jagdalpur-Bhubaneswar express were derailed at around 11:00 pm (1730 GMT) on Saturday.The accident happened near Kuneru railway station in the remote district of Vizianagaram in Andhra Pradesh state.
"The death toll has gone up to 32, unfortunately. But it should settle at that. It shouldn't rise any further," J. P. Mishra, a spokesman for East Coast Railways, told AFP.
He said some 50 injured have been moved to nearby hospitals.
The accident came only two months after nearly 150 people were killed in a similar disaster, highlighting the malaise on a network which is one of the world's largest.
National railway spokesman Anil Saxena said government officials and emergency workers worked through the night to try to find survivors.
Saxena said investigators were considering possible sabotage of the tracks by Maoist rebels, who were active in the area.
"It is being looked into, it is one of the many angles we are looking into," he told AFP.
"There is some suspicion (of sabotage) because two other trains had crossed over smoothly using the same tracks earlier in the night."
Television footage showed a line of carriages lying on their sides as rescuers in neon orange safety vests and hard hats tried to hoist passengers through the windows while locals looked on.
Workers carried a half-naked passenger covered in dust on a stretcher out of a tilted carriage. Another TV image showed a man lying faced down, crushed under mangled heaps of wreckage.
Injured victims lay on hospital beds and stretchers, their limbs swathed in bandages.
Mishra told the NDTV news network there were some 600 people in the carriages that derailed.
He added that 10 buses have been arranged for passengers who escaped injury to travel to Bhubaneswar, capital of neighbouring Odisha state.
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Frequent accidents
The train was travelling from the city of Jagdalpur to Bhubaneswar when it came off the track nearly 160 kilometres (100 miles) from Visakhapatnam, the nearest city to the accident site.
Rail traffic on the coast line has been suspended.
Chief ministers of Odisha and Andhra Pradesh expressed their grief over the latest tragedy, while Railway Minister Suresh Prabhu said he was rushing to the spot.
Prabhu announced compensation of 200,000 rupees ($2,936) for the relatives of the dead and 50,000 for those injured.
India's railway network is still the main form of long-distance travel in the vast country, but it is poorly funded and deadly accidents occur relatively frequently.
On Friday 10 coaches of an express train were derailed in the western state of Rajasthan, leaving many passengers with minor injuries.
The latest deadly incident comes two months after 146 people were killed when a passenger train was derailed near Kanpur, in the northern state of Uttar Pradesh, in one of the country's worst rail disasters for decades.
Last month two people were killed and dozens injured after another train derailed also near Kanpur.
In 2014 an express train ploughed into a stationary freight train, also in Uttar Pradesh, killing 26 people.
A 2012 government report said almost 15,000 people were killed every year on India's railways and described the loss of life as an annual "massacre".
Prime Minister Narendra Modi's government has pledged to invest $137 billion over five years to modernise the crumbling railways, making them safer, faster and more efficient.
Writing on Twitter, Modi sent his condolences to the victims' families.
"My thoughts are with those who lost their loved ones... the tragedy is saddening," said the prime minister.
Modi's government has signed numerous deals with private companies to upgrade the ageing network.
Japan has agreed to provide $12 billion in soft loans to build India's first bullet train, though plans remain in their infancy.
