At least 32 people have been killed and dozens injured after a construction crane fell on a passenger train in north-eastern Thailand, officials have said.

The crane, which was being used to construct an elevated high-speed railway, fell on the moving train on Wednesday morning, local time, causing it to derail and catch fire.

A large red crane has collapsed onto a concrete bridge. Underneath is a destroyed train carriage. People stand around.

The crane fell on a moving train in north-east Thailand. (Supplied: Fire & Rescue Thailand)

The accident occurred in the Sikhio district of Nakhon Ratchasima province, 230km north-east of Bangkok. It was travelling from the capital to Ubon Ratchathani province.

The Thai health ministry has said that at least 32 people were killed and 64 people were taken to hospital, seven in serious condition.

A train carriage has derailed and is heavily damaged and lying on its side.

Authorities are still searching for bodies after the incident. (Reuters: Ministry of Transport)

From a hospital bed in Nakhon Ratchasima, survivor Taew Eimertenbrink, 63, said her German husband “was killed instantly” in the derailment.

“I was sleeping. He was sleeping. A metal bar was on him,” she told reporters.

The couple was visiting from Germany and travelling to Taew’s hometown in Surin province, she said.

“I thought travel by train was the best way, but… this happened.”

Local resident Mitr Intrpanya, 54, told AFP he heard a “loud noise, like something sliding down from above, followed by two explosions” at around 9am.

“When I went to see what had happened, I found the crane sitting on a passenger train with three carriages,” he said.

“The metal from the crane appeared to strike the middle of the second carriage, slicing it in half.”

Transport Minister Phiphat Ratchakitprakarn said in a statement there were 195 passengers on board and that he had ordered a ‌thorough investigation to be carried out.

Those killed were in two of the three carriages hit by the crane, he said.

Dozens of rescuers walked around the twisted metal carriages, searching with sniffer dogs for people still inside, while others used cranes from the high-speed rail project contractor Italian-Thai Development to remove debris.

A rescue teams stand near a damaged train with a crane in the background

Rescuers worked to try and free those trapped in the train. (AP Photo: Sakchai Lalit)

The firm expressed condolences, and promised to compensate the victims’ families and cover medical expenses for the injured.

Thai Prime Minister Anutin Charnvirakul, visiting the scene hours after the accident, said it was “clearly the fault of the construction company”.

“We must determine the cause so this incident can serve as a lesson,” he told reporters.

Thailand’s state rail operator said it ordered Italian-Thai to halt construction until an investigation was completed.

The accident happened at a construction site that is part of a more than $5 billion ($7.47b) project backed by China to build a high-speed rail network in Thailand.

It aims to connect Bangkok to Kunming in China via Laos by 2028 as part of Beijing’s vast Belt and Road infrastructure initiative.

Thailand has around 5,000 kilometres of railway but the run-down network has long driven people to favour travel by road.

Upon completion of the 600-kilometre high-speed railway, Chinese-made trains will run from Bangkok to Nong Khai, on the Mekong River border with Laos, at up to 250 kilometres per hour.

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