The teenager had arrived in Malaysia with her parents on Saturday for a two week holiday.
They checked into The Dusun resort in Serembam on the edge of a rainforest near Kuala Lumpur, The Sun reports.
It was reported that when her parents woke up at around 6:30am on Sunday morning, they found her missing and the window of her hotel room was open, which panicked her parents.
The disappearance in Malaysia of a 15-year-old London schoolgirl is now being treated as both an abduction and a missing person case by police, a charity has said.
The trust says it has been informed that Nora's family "are with police now".
Her father raised the alarm when he discovered her missing from her bedroom at 8am yesterday.
"She is 15 with special needs, and hasn't been seen since everyone went to bed last night", Dominic Graham said in a Facebook post on Sunday.
"Based on preliminary police probe, the family comprising a couple and three children from Ireland had checked into the resort at 7am on Aug 3".
Catherine Morrison, a friend of the family, estimated that by noon United Kingdom time she had already been missing for 12 hours.
"Nora is a child with special needs and has learning and developmental disabilities which make her especially vulnerable and we fear for her safety", the girl's aunt, Aisling Agnew, told the network.
According to BBC, a family friend had described the disappearance as "completely out of character" and said Quoirin's parents were "frantic".
The Irish embassy in Kuala Lumpur said it was providing consular assistance to Quoirin's family.
"I'm a mother and I burst into tears just hearing this story", she said.
A desperate search has been launched for Nora Quoirin, 15, who has learning difficulties.
"I just ask for anyone who can help them to do so as soon as possible".
A police team assisted by personnel from the Fire and Rescue Services Department had conducted a search in the area. "The hotel have been really helpful", she said.