The body found in Malaysia on Tuesday after a massive search is that of Franco-Irish teen Nora Quoirin, who disappeared 10 days ago from a rainforest resort, police said.

"The family has confirmed it is the body of Nora," Mohamad Mat Yusop, police chief of Negeri Sembilan state, said.

The 15-year-old went missing on August 4, a day after checking into the resort with her London-based family. They suspected she was abducted but Malaysian police classified it as a missing person case.

The body was found in a small stream in a ravine about 2.5km from the resort, Malaysia's deputy national police chief Mazlan Mansor said. It was transported by helicopter to a nearby hospital, where her parents positively identified her.

The body was unclothed but he declined to reveal if it had any injuries. Mazlan said it was still being treated as a missing person case.

A post-mortem will be conducted Wednesday morning, he said.

More than 350 people were deployed to hunt through dense jungle next to the Dusun Resort, not far from Kuala Lumpur, backed by helicopters, drones, sniffer dogs and divers.

Shamans conducted rituals in an effort to locate her while the investigation was assisted by police from Britain, Ireland and France.

The Lucie Blackman Trust, a UK charity that supports the families of British people missing overseas, said a body had been found.

"At this time we cannot confirm it is Nora. However it sadly seems likely. Investigations are underway to confirm identity and cause of death," said a statement from the group.

The charity did not give further details. Malaysian officials did not immediately comment.

As news emerged a body had been found, police vehicles were seen racing to an area not far from the resort.

The discovery came a day after her family offered a 50,000 ringgit (S$16,531) reward, donated by a Belfast business, for information that could lead to her return.

The schoolgirl "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", said a family statement.

At one point, her mother Meabh fought back tears as she made an emotional speech thanking the search team, with the girl's French father Sebastien by her side.

The five-hectare resort where the teenager disappeared from is next to a patch of thick jungle and in the foothills of a mountain range.

Her family said it would be extremely unusual for the reserved youngster to have wandered off on her own.

She has a condition called "holoprosencephaly", which means she has a smaller-than-normal brain, limited verbal communication and cannot write more than a few words.

She attended a school for young people with learning and communication difficulties.

While officially treating it as a missing person case, police did not rule out other possibilities.

An open window was found in the cottage where the family was staying at the resort.

Police have questioned a number of people, are examining fingerprints found on a window, and looking into reports that villagers heard a truck early on the morning that the girl disappeared.