URDA, Spain: A high-speed train collision south of Madrid killed 68 people and injured scores more on Wednesday, with the toll likely to rise, authorities said, in one of Europe's deadliest such disasters this century.

The second such accident to strike Spain this year will raise fresh questions about the country's rail safety, with the transport minister speaking of an "error" and "inexplicable circumstances" that led to the collision.

AFP reporters on the scene in the central region of Castilla-La Mancha saw one train embedded into another and some carriages lying on their side in tangles of metal debris at the bottom of an embankment.

Dozens of emergency services vehicles were racing to and from the site during a frantic search for survivors, while several black vans arrived from a funeral parlour.