(CNN)A 15-year-old girl with a learning disability has gone missing while on holiday in Malaysia, in what police are treating as a possible abduction.
Nora Quoirin, from London, was staying at a resort in a nature reserve 39 miles south of the capital, Kuala Lumpur.
Her father discovered she was missing from her room at 8 a.m. local time on Sunday, and noticed that her window was open, according to the Lucie Blackman Trust (LBT) charity, which is assisting the family.
Malaysian police have told the family the incident is being treated as both an abduction and a missing person case, the group told CNN.
Quoirin, who has an Irish mother and a French father, was traveling on an Irish passport during the trip. The Dusun resort, where the family were staying, is in a remote area 800 feet above sea level, in the Titiwangsa mountain range.
"This is a very vulnerable young girl missing in a remote location. She has been missing for over 24 hours now and it is imperative that every resource available is deployed to search for her," LBT's chief executive, Matthew Searle, said in a statement.
"It is possible she has been seen or taken in by somebody and is unable to communicate, so we urge everyone who can to share our appeal poster and social media appeals," he added. "Sadly it is also possible that Nora has been the victim of serious crime -- we urge anyone with any information to come forward."
In a statement posted online, the management of the Dusun resort said that hotel staff searched the 12 acre (48,562 square meter) property "all Sunday morning," before then joining the wider police search of the surrounding area.
Aisling Agnew, the girl's aunt, was quoted by LBT as saying: "Nora's parents and relatives in Ireland and France are distraught by her disappearance. Nora is a child with special needs and has learning and developmental disabilities which make her especially vulnerable and we fear for her safety."
"Nora would not know how to get help and would never leave her family voluntarily. We now consider this a criminal matter. We are appealing to everyone to assist the local police in any way they can and to pass on any information that would help locate our beloved Nora without delay."
The family have set up an email address for information -- email@example.com -- and the LBT has encouraged anyone with information about her disappearance to call +44 8000 988 485.
CNN has contacted the Irish Department of Foreign Affairs and the Malaysian Embassy in London for comment.