Bones have been found close to where the British hiker Esther Dingley went missing last year.
Ms Dingley, an experienced hiker, was last seen on the Pico Salvaguardia in the Pyrenees, on the border between France and Spain, on Nov 22.
She and her partner Dan Colegate had left England in 2014 to go on an adventure of a lifetime, which had been intended to last 12 months but stretched to six years.
The 37-year-old sent a selfie to Mr Colgate from the 9,000ft Pic de Sauvegarde on the day she went missing and has not been heard from since.
French police say they are now analysing the bones in an attempt to confirm whether they are human remains.
A mountain runner raised the alarm at around 2pm Friday after discovering what he believed could be the remains of a body. Spanish police went to the area and alerted their French counterparts after discovering that the location was just over the border.
French officers have now taken charge of the investigation to try to confirm whether the bones are human and, if so, whose they are. Spanish police sources said the bones appeared to be human.
A Civil Guard source said: "A mountain runner has found what could be human bones just over the French side of the border at Puerto de la Glera. They appear to be human remains, but it will be up to French police now to analyse them."
Another Spanish source said it appeared "90 per cent certain" that they were human remains.
Specialist officers from Spain and France have carried out several searches of the area around the Puerto de la Glera hiking trail. The search was halted in December due to the heavy snow, and resumed last month.
Mr Colgate said in a recent BBC interview he "could no longer agree" with the idea that Ms Dingley had suffered an accident. He said: "The search has been so prolonged and so intense that as far as I'm concerned the probability of an accident is now less than the probability of a criminal act."