Spanish prime minister Pedro Sanchez speaks to the media at the scene of a collision between two high-speed trains in Urda, Toledo. (EPA Images pic)MADRID: The death toll from a collision between two high-speed trains in central Spain rose to at least 68 on Wednesday, as prime minister Pedro Sanchez pledged a thorough investigation into the disaster, Anadolu Ajansi reported.

Speaking at the crash site in Urda, Toledo, Sanchez said authorities would determine the cause of the accident and take action if wrongdoing was uncovered, Spanish news agency EFE reported.

"We will get to the bottom of this. If there has been negligence, it will be known," he said.

Sanchez announced three days of national mourning from Oct 29 to 31, saying it was "unacceptable for a country like Spain" to experience two high-speed rail accidents in a single year.