Malaysian police have denied that the disappearance of a 15-year-old London schoolgirl is being treated as a possible abduction, contradicting a statement from a charity supporting her family.

Nora Quoirin, who has special needs, is the daughter of an Irish-French couple who have lived in London for about 20 years. She went missing while on holiday with her family at the Dusun resort in a nature reserve near Seremban, 40 miles south of the capital, Kuala Lumpur. The resort is adjacent to the 4,000-acre (1,600-hectare) Berembun forest reserve.

The Lucie Blackman Trust, a charity which works with British nationals facing overseas crises and is helping the family, said in a Facebook post on Monday that the police were now treating the case as a possible abduction as well as a missing persons case.

After Malaysian police insisted that it was not being treated as an abduction, the charity said: “Contrary to several reports that police are NOT treating Nora’s disappearance as an abduction, the family have been told directly by police that they are treating it as both an abduction and missing persons case.”

Nora’s father raised the alarm when he discovered her missing from her bedroom at 8am on Sunday. Her window had been opened. Police said they have dispatched more than 100 officers and sniffer dogs in the resort and surrounding areas.

LBT’s chief executive, Matthew Searle, said: “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.”

Nora’s aunt Aisling Agnew said her parents and relatives in Ireland and France were distraught. “Nora is a child with special needs and has learning and developmental disabilities which make her especially vulnerable and we fear for her safety,” she added. “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.”

A family friend, Catherine Cook, said it was out of character for Nora to wander off. “I’m a mother and I burst into tears just hearing this story. I cannot imagine the hell that they are living right now.”

Nora is understood to have been travelling on an Irish passport.

A spokesman for Ireland’s Department of Foreign Affairs said consular assistance was being provided.