AT least 22 people have been killed and 30 more have been injured after two passenger trains collided in the Puglia region of Italy, firefighters have said.

The two trains were travelling on a single-track line between the coastal towns of Bari and Barletta in the country's olive region when they crashed into each other around 11.30 am local time.

Emergency services are at the scene near the town of Andria and are trying to free passengers from the wrecked carriages.

An image of the crash showed the carriages had been badly damaged and forced off the rails at sharp angles, with debris strewn across either side of the tracks.

"Unfortunately the death toll has risen to 20," said Giuseppe Corrado, the deputy head of the local province. He said four people had been "seriously" injured and appealed for blood donors to go to local hospitals.

He said other passengers had been taken to hospital with less severe injuries.

A field hospital was set up in the nearby countryside to treat the injured, who are also being transported to hospitals.

"We are working with dozens of rescue teams to open up the carriages," said Luca Cari, a fire service spokesman.

"The rescue is complicated because this happened in the middle of the countryside," he added.

A small child was rescued from the wreckage and taken to hospital in a helicopter.

"Some of the cars are completely crumpled and the rescuers are extracting people from the metal, many of them injured," Riccardo Zingaro, the chief of the local police in Andria, told ANSA at the scene. ​

National police and carabinieri could not immediately provide details about the extent of the crash.

Massimo Mazzili, the local mayor for the town of Corato, posted several photos of the crash on his Facebook page

He said: "It is a disaster, as if a plane crashed.

"The emergency workers and civil protection staff are there, unfortunately there are victims."

Italy's prime minister Matteo Renzi said the crash "is a moment of tears", and pledged not to stop until a cause is determined.

He said Granziano Del Rio, Italy's minister for infrastructure and transport, is heading to the crash site with the head of civil protection.

Mr Renzi interrupted a trip to Milan to return to Rome following the accident.

Pope Francis has offered his condolences to the families of the victims.

He sent a telegram to the archbishop of Bari, Monsignor Fracnesco Cacucci, saying he shared in the pain of so many families and was praying for the recovery of those injured.

Thousands of people use the line, managed by Ferrotramviaria, each day.

The last major rail disaster in Italy was in 2009, when a freight train derailed in Viareggio, in the centre of the country. More than 30 people living close to the tracks died in the subsequent fire.

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