HUELVA, Jan 29 - Some relatives of the 45 people killed in Spain's rail disaster vowed on Thursday to find out why the two high-speed trains collided, making their promise before survivors still wearing bandages and slings at a funeral mass.

"Only the truth will help us heal this wound. We will know the truth, we will fight so that there will never be another train," Liliana Saenz, who lost her mother, said at the service in the southern city of Huelva. King Felipe VI and Queen Letizia attended.