The family of 15-year-old Nora Quoirin, who has been missing in Malaysia since August 4, are offering £10,000 for information that leads to the return of their daughter.
Nora, who was born with learning difficulties, had been on a family holiday at a resort near Seremban, around an hour south of capital Kuala Lumpur, when her father discovered she was not in her bedroom.
On Monday her parents released a statement in which they appealed for information which may help in the search for her, and also offered a reward.
"Nora is our first child. She has been vulnerable since the day she was born," Meabh Quoirin, Nora's mother said.
"She is so precious to us and our hearts are breaking.
"We are appealing to anyone who has information about Nora to help us find her.
"The police have been working extremely hard to bring Nora home.
"In order to help their investigation, we have decided to offer a reward: 50,000R [ringgit] has been donated by an anonymous Belfast-based business for any information that directly helps us to find Nora."
A team of more than 300 search and rescue personnel have been looking for Nora since her disappearance, trawling dense forest and playing her mother's voice over loudspeakers in a bid to find her.
Nora's family have said she is not able to properly take care of herself and seems much younger than her age.
They maintain that she has been abducted, saying that she would not wander off by herself.
A fundraising page, set up by Nora's aunt, has gathered more than £91,000 in donations.
A second page, set up by her uncle to collect money in euros, now has more than £13,000 worth of donations.
Fresh attempts to find Nora started on Monday, with the biggest search team to date hunting for her.
The Malay Mail, a newspaper in the south-east Asian country, reported a team of 348 are taking part in the hunt.
It comes after a new hotline was set up to gather information on the whereabouts of the Londoner.
Her parents, Meabh and Sebastien Quoirin, a French-Irish couple who have lived in the capital for two decades, thanked those involved in looking for her.
In a video broadcast on local media, Ms Quoirin said: "We want to say thank you to each and every one of you.
"We know you’re searching night and day for Nora.
"We see you working so hard and also praying with us and being with us."
The family have said they remain hopeful after police leading the investigation refused to rule out a "criminal element".
The National Crime Agency and the Metropolitan Police are supporting the Malaysian police with the case.
A spokesperson for the National Crime Agency said: "The National Crime Agency, the Met Police and the Irish police are working together to help and support the Malaysian authorities relating to Nora Quoirin’s disappearance."
Anyone with information is asked to contact the Lucie Blackman Trust (a charity which helps the families of missing Brits abroad) using email@example.com or +44 800 098 8485.