Police in Malaysia have said a post-mortem examination on the body of Nóra Quoirin has so far failed to establish a cause of death.

Speaking at a news conference outside the hospital, they said four pathologists, including one from the capital Kuala Lumpur, had spent eight hours examining her body.

A further update is expected tomorrow.

Nóra's body was found yesterday by volunteer rescue workers in the Dusun rainforest resort.

The 15-year-old went missing from the resort on Sunday 4 August, triggering a major search operation involving hundreds of members of the emergency services and the public.

No trace of her was found until yesterday afternoon, when her body was located around 2km from where she was staying with her family.

"The post-mortem is ongoing, therefore no conclusion has been reached yet," said Matthew Searle of the Lucie Blackman Trust, which is assisting the family.

He added: "There will be a time for comment, but that time is not now. Let the family grieve in peace."

In an emotional statement, her devastated family said their "hearts are broken" after the discovery, but also offered their thanks to those involved in the search.

Describing how the teenager had "truly touched the world", her family said: "Nóra is at the heart of our family. She is the truest, most precious girl and we love her infinitely.

"The cruelty of her being taken away is unbearable. Our hearts are broken. We will always love our Nóra."

The family added: "We would like to thank all the people that have been searching for Nóra and trying their best to find her.

"We thank the local people here and those far and wide for their prayers and support at this time.

"Nóra has brought people together, especially from France, Ireland, Britain and Malaysia, united in their love and support for her and her family.

"To all our friends and family at home, we can't thank you enough for all your love."

Family lawyer Sankara N Nair said the family expected the police to do a thorough investigation, "including criminal angles".

He urged Malaysian police to accept an offer by French Foreign Minister Jean-Yves Le Drian to help investigate the circumstances of the death.

"It's a very good proposal," he said. "I hope police will accept the assistance."

Mr Nair added that Nóra's family were "highly traumatised following the loss of their child. They are in a state of shock".

Nóra, who was born with the brain defect holoprosencephaly, disappeared just a day after arriving at the resort with her family.

Hundreds of people were involved in the search and rescue operation and it was volunteer helpers who found her body.

Deputy police chief Mazlan Mansor told reporters at a press conference that the remains were winched by helicopter to a hospital mortuary.

He added that while it remained a missing persons case police were looking into all possibilities including the "angle of criminal investigation".

The teenager's parents, Meabh and Sebastien Quoirin, a French-Irish couple who have lived in London for 20 years, had thanked those looking for her as fundraising pages set up by Nóra's aunt and uncle collected more than €100,000 from well-wishers.

Following the confirmation that Nóra's body had been found President Michael D Higgins and his wife Sabina offered their "deepest condolences" to her parents, to her siblings and to her extended family.

Taoiseach Leo Varadkar said that the situation was "every family's worst nightmare".

He tweeted: "Our thoughts & sincere condolences are with Nóra Quoirin's parents, siblings & wider family at this unimaginably difficult time.

"They have experienced every family's worst nightmare. I'd like to pay tribute to everyone who searched for Nóra. May she rest in peace."

In Belfast, a book of condolence has opened for the 15-year-old teenager. 

Sinn Féin Lord Mayor John Finucane was the first to sign at the city hall, followed by a queue of other elected representatives and well-wishers.

He said: "It is heart-breaking. I don't think this is something that would be easily dealt with in any circumstance but the fact that they are so far away from home in Malaysia.

"This is a family that was on holiday, this is a girl who was vulnerable and I think the family have been through hell in the past few days.

Yesterday, a special service was held at the South Belfast church in which Nóra was baptised in. Her grandparents are parishioners.

The French Foreign Ministry also expressed its sincere condolences to Nóra's family.

The Quoirins had said Nóra's condition meant she was not independent and had difficulty walking.

Search crews looking for the teenager had played her mother's voice in the dense Malaysian forest near where she disappeared.

Police had said Nóra, who was travelling on an Irish passport, was believed to have climbed out of her resort room window.

After Nóra went missing, her family described how she was particularly vulnerable. Describing her as a "very special person", they said she would not have gone anywhere alone.

Additional reporting PA