Twenty-four people have died after a train derailed in northwestern Turkey when heavy rain caused the ground under the rails to collapse, the Turkish deputy prime minister has said.

The train was en route to Istanbul from Kapikule on the western Bulgarian border, with 362 passengers and six crew members on board. Five of its six cars derailed.

Health minister Ahmet Demircan said 318 people were injured, with around 124 of those still being treated in hospitals after helicopters ferried many of the wounded from the scene.

Television footage showed rescuers heading to the crash site and victims being pulled from the carriages.

The Anadolu news agency said Recep Akdag, the deputy PM, had announced search operations have now been completed at the crash site where the wreck of the train remains.

Seven other trains had used the same route earlier on Sunday but the rain caused "extraordinary swelling", according to transport minister Ahmet Arslan.

CNN Turk, however, reported that the accident was caused by a collapsed bridge in the western province of Tekirdag.

A media ban was issued on Sunday by the government, which cited national security and public order concerns, before it was lifted on Monday.

However, international media struggled to ascertain further details around the crash.

Russian news sources said that Russian tourists were among those injured in the derailment.

President Recep Tayyip Erdogan's office said ministers had informed him about the incident and that he sent condolences for those killed.

Judicial and administrative investigations were launched.