Two high-speed trains have collided in Spain in what the country’s prime minister has described as a “serious” incident.

Rescuers searched desperately through wrecked carriages on Thursday in the hope of finding more survivors of Spain's second deadly high-speed train crash this year, which has so far claimed 68 lives.

A least 10 people are dead, regional government spokesperson for the Junta de Castilla-La Mancha region Esther Padilla has told local television.