A ‍train has derailed in Thailand after a construction crane crushed two of its carriages, killing at least 32 people and injuring 66.

The crane was working on a high-speed rail project when it collapsed and hit the passing train, causing it to derail and briefly catch fire on Wednesday.

Transport Minister Phiphat Ratchakitprakarn said there were 195 people aboard the train, adding that he had ordered a thorough investigation.

Pictures from the grim scene show train carriages overturned next ​to bushland and firefighters extinguishing a blaze as smoke billowed out.

Bodies were being pulled from the crushed and smouldering wreckage as rescuers raced to find survivors.

The passenger train burst into flames after the impact. Photo: Thai Transport Ministry

Earlier footage of ‌the crash site verified by Reuters showed rescue workers trying to extract casualties from a mangled carriage, with some badly injured passengers being loaded into ambulances.

Part of the collapsed crane were still propped up ‍by concrete stanchions built to support the rail link, with debris dangling over the tracks below.

The tragedy happened in the Sikhio district of Nakhon Ratchasima province, 230 kilometres north-east of Bangkok.

The train was on its way to Ubon ⁠Ratchathani province from Bangkok.

The elevated high-speed rail ​project, one of several being built in Thailand, was being built above the existing rail line.

The construction is part of the Bangkok-Nakhon Ratchasima segment of the high-speed rail project linking the Thai capital with the south-west Chinese city of Kunming.

Rescuers search the wreckage for survivors. Photo: AAP

Prime Minister Anutin Charnvirakul told the State Railway of Thailand to provide good compensation for families of the dead, adding after being briefed at the scene: “We need to investigate… ‌and take legal ​action.”

The Italian-Thai Development Public Company, which was contracted to build the rail segment, expressed regret for the accident and said ‍it would provide compensation and relief to families of casualties.

In March last year, a 30-storey building under construction in Bangkok by a joint venture including ITD collapsed, killing 89 people, after an 8.8-magnitude earthquake struck neighbouring Myanmar.

ITD president Premchai Karnasuta was indicted in August along with 22 others on allegations of negligence and breaching construction regulations.

He and 14 others denied wrongdoing when they were arrested in May.

Recovery operations at the ​accident ​scene continued into Wednesday night, with Anutin saying the track needed ​to be cleared by the end of the week.

He noted that it ​was a major rail route and delays would hurt the regional economy.

Chinese Foreign Ministry spokeswoman Mao Ning said the government attached great importance to the safety of projects and personnel in Thailand and was investigating.

“At present, it seems that the relevant section was under construction by a Thai enterprise. The cause of the accident is still under investigation,” she said.

The cross-country high-speed rail project will connect to China through Laos.

The government said last year that more than a third of construction had been completed in the segment connecting Bangkok to Nakhon Ratchasima. The whole line to Nong Khai at the border ‍with Laos is expected to be ready by 2030.

-with AAP