Police Scotland are working with Europol and Spanish officers in the search for a man last seen in Tenerife almost four months ago.
Alan Jeffrey, 25, was last seen by his girlfriend on June 10 on the popular holiday island.
He was due to return home with her that day but said he was going to stay on with some friends, and his girlfriend then returned home by herself.
Mr Jeffrey, from Wishaw, North Lanarkshire, has not been in touch with his family since then and he was reported missing to Police Scotland on June 26.
Officers said it is unusual for the 25-year-old not to be in touch with his family and given the passage of time, they cannot rule out that he may have come to harm.
Inspector Keith Campbell said: “Whilst it may seem an unusual move for police in Scotland to be investigating a person missing in Spain, we are liaising with Spanish authorities and Europol with our inquiry.
“All of Alan’s family, friends and associates are here in Scotland and he was reported missing here. A number of officers have been working on this inquiry for some time, however it has been challenging as we haven’t received much information so far, and this is why we are now appealing to the public for their help.
“Given the passage of time and with some of the information we have received, we cannot rule out that some harm may have come to Alan.
“He may have decided himself not to return home, however it is very unusual for him not to be in touch with his family for such a long period of time.”
When last seen, police said Mr Jeffrey had indicated he was planning to travel to Marbella in Spain with some friends.
Mr Campbell added: “We remain focused on tracing him safe and well.
“If Alan himself is reading this appeal, please get in touch with your family as they are very concerned.
“I would ask anyone who may have information in relation to this inquiry to contact police via 101.”