The family of hiker Lily Hooper says they are “absolutely devastated” that their beloved daughter is still missing amid a wide-scale search.

Hundreds of rescuers have trawled bushland in NSW’s Southern Highlands for days, looking for the 18-year-old.

The Oakdale teenager has not been seen since last Wednesday, when she embarked on a hike in the Nattai National Park.

She did not return that night and could not be contacted on her mobile phone, triggering the searches.

“Our family is absolutely devastated that our beloved daughter Lily is missing,” said a statement on Tuesday night.

“We desperately want to bring Lily home safe and we ask as the search continues, to keep our family and Lily in your thoughts.”

The family thanked the emergency services and volunteers for their support and commitment to the search — “not only during the day but throughout the night”.

“We appreciate people who have made offers for the search but, due to the terrain and conditions, we ask just professional search teams continue,” they said.

“We also ask for privacy and understanding as our family navigates this unimaginable situation.”

Hundreds of emergency personnel, loved ones and volunteers battled unforgiving conditions across the weekend to no avail.

Detective Inspector Brendan Bernie said a “rescue” remained core to his mission.

“We’re treating it definitely as a search and rescue operation and we suspect that Lily is out somewhere in this bushland and nearby,” he said on Monday.

“Lily’s an experienced bushwalker. We’re relying on that experience to get her through this ordeal and we’re still hoping that she’s found alive and safe.”

Searchers have found no trace of Hooper since they discovered her car at the Bonnum Pic trailhead on Wednesday night.

Earlier on Monday, a man who identified himself as Hooper’s father asked Australians to cross their fingers for his daughter.

“I want to just project positive energy and love, and we’re going to find her today,” he said in an on-air appeal on Sydney’s 2SM Radio.

“We’re going to find her today. I’m going back to her now.

“I’m just putting my boots on, and I just want everyone to throw love and energy because we’ve got to go and find her.

“She’s got to be there somewhere.”

The ongoing search includes crews from NSW Police, the Rural Fire Service and the State Emergency Service.

Rescuers have faced rugged, dense terrain in the national park, and cold, wet and foggy weather.

Police are using a thermal imaging helicopter at night, and earlier revisited any telecommunications data potentially emitted by Hooper’s phone.

-with AAP