Nora Quoirin's parents awoke to find her missing from her hotel room, with the window open.
They're already using sniffer dogs and recordings of the mother's voice calling Nora's name in attempts to find her.A 15-year-old girl from London has gone missing while on holiday in Malaysia, a friend of her family has said.
Nora Quoirin, who has learning difficulties, arrived there with her family on Saturday for a two week "trip of a lifetime".
They were staying in the town of Seremban, on the edge of rainforest near Kuala Lumpur.
When her parents awoke on Sunday morning they found her missing and the window of her hotel room open.
Catherine Morrison, a friend of the family, estimated that by noon UK time she had already been missing for 12 hours.
Image copyrightFAMILY HANDOUTImage captionNora went missing the day after she and her family arrived in Malaysia
A spokesman for the Irish Department of Foreign Affairs said: "We are aware of the case and providing consular assistance."
Malaysian Police are said to be using sniffer dogs in the search for Nora.
Although her family have been resident in the UK for at least two decades, she is thought to have been travelling on an Irish passport.
Ms Morrison described the disappearance, which was discovered at about 06:30 local time, as "completely out of character" and said her parents were "frantic".
She said: "They had just arrived - it was going to be a trip of a lifetime.
"They checked into their hotel, the Dusun - it looked beautiful with little cottages and an infinity pool.
"They went to bed, but this morning Nora was not in her room and the window was open."
"Police are looking for her with sniffer dogs. The hotel have been really helpful," she said.