Police have revealed new details about two friends who went missing on a camping trip in the Victorian Alps in Gippsland a month ago.

Key points: Victorian detectives say Russell Hill suffered from a heart condition and purchased a high-end drone before he disappeared during a camping trip

Victorian detectives say Russell Hill suffered from a heart condition and purchased a high-end drone before he disappeared during a camping trip Mr Hill's family said Carol Clay, who went missing with Mr Hill, has been a close friend for years

Mr Hill's family said Carol Clay, who went missing with Mr Hill, has been a close friend for years Police still have not worked out what caused a fire at the pair's campsite, or whether or not their disappearance involved foul play

Drouin resident Russell Hill, 74, and Carol Clay, 73, were long-time family friends who went camping along the Wonnangatta River on March 19.

Police said Mr Hill collected Ms Clay from her Pakenham home at 7.30am on Thursday, March 19.

Mobile phone tracking data showed the pair drove through Heyfield, Licola and Licola North to get to the Wonnangatta Valley.

"They then took the Zeka Spur Track, which leads up into the High Country, into Wonnangatta, which is getting close to as remote as you can get in Victoria," Detective Inspector Andrew Stamper said.

Mr Hill last made contact with his wife and friends on March 20 via radio from Wonnangatta Station.

He was expected to radio the group again the following night.

Mr Hill's wife and Ms Clay's family thought each of them was camping alone, but police declined to speculate further about the nature of their relationship.

"It is delicate and we are being very respectful of both families wishes and concerns here," Detective Inspector Stamper told ABC Radio Melbourne.

"Both of these people have large and loving families who are grieving at the moment, and they want answers about where their loved ones are."

'Meticulous' camper had health issues

Police said Mr Hill, a former logger who knew the area well, suffered from various medical ailments, including heart and skin conditions.

"We know that he had spent quite a bit of time up here and he was described to us as being quite meticulous when camping," Acting Inspector Dave Fyfe said.

"With that in mind we don't believe he would have come up here unprepared."

Some of the old mine shafts in the area have been checked as part of the investigation, which has been taken over by Missing Persons Squad detectives.

"The area is incredibly remote and there is a possibility that they have suffered some misadventure in the bush," Detective Inspector Andrew Stamper said.

"But we also need to rule out any possibility of foul play."

Mr Hill used an amateur HAM radio call sign VK3-VZP across a number of channels when he went camping.

Police are urging anyone who can recall hearing any radio communications by Mr Hill to contact them.

A camper in the Wonnangatta area supplied this photo to ABC Gippsland. It has been verified by police. ( Supplied )

Drone missing, fire still a mystery

Arson detectives have been unable to work out what caused a fire that destroyed camp chairs, a table and a tent at their campsite at Dry River Creek Track near the Wonnangatta campground.

A photo obtained by ABC Gippsland showed the charred campsite and Mr Hill's car with scorch marks.

Police say the well-equipped utility contained some of Ms Clay's belongings and was in working order with the keys when the campsite was discovered by other campers at about 2pm on March 21.

Anyone who saw smoke from that fire is urged to get in touch with detectives

Police have also revealed that Mr Hill purchased an expensive DJI brand Mavic drone before the trip and believe it could hold vital clues.

"We still can't find that drone," Acting Inspector Fyfe said.

"If someone has recovered it, we'd really like them to come forward."

Carol Clay was a former CWA president. ( Supplied )

'Absolute mystery'

Spokespeople for both families thanked everyone who had been involved in the search for Mr Hill and Ms Clay, and called for any witnesses to contact police.

"Russell is our brother, husband, dad and pa, and Carol has been a friend of the family for a long time," a spokesperson for Mr Hill's family said.

"The police, SES and volunteers have searched extensively, and we thank them wholeheartedly.

"It is devastating for our family that we don't know what has happened to them both.

"We are pleading for anyone who has any information to please come forward."

Ms Clay's family said the pair's disappearance was very out of character.

"We are living with uncertainty, loss and the continual stress of not knowing where they are and what has happened," the family said in a statement said.

"At this time, we ask that our privacy be fully respected while we deal as a family with the ongoing process of supporting each other, dealing with the issues this raises, and helping the police.

"We would also very much like to take this opportunity to extend our thanks and gratitude to the many people who have taken part in the search in difficult terrain and those who are continuing to work hard to solve what is, at this stage, an absolute mystery."

'Last weekend of free travel'

Police said there had been "much speculation" about the pair's disappearance in the community.

Sorry, this audio has expired Missing Wonnangatta campers not expected to be found alive, police say

"If you do have some information that you might have felt uncomfortable speaking with police about previously, then we really need you to come forward now and help up try and find Russell and Carol as soon as possible," Detective Inspector Stamper said.

"This was really the last weekend in Victoria where people could freely travel about, so there were potentially a number of people in the area who could have seen Russell and Carol.

"If there were any hunters, campers or motorcyclists who were in the area around this time, then we'd like to speak to you.

"Please don't feel worried that police are looking to catch anyone out with regards to non-essential travel.

Police say Mr Hill and Ms Clay were camping in one of the most remote areas in the state. ( Supplied: Victoria Police )

"We're also keen to know if they stopped anywhere on the journey up and if anyone has CCTV footage," Detective Inspector Stamper said.

"Any piece of information or footage could prove crucial at this point.

"At this stage we are at a loss to say exactly what has happened to Russell and Carol.

"We don't know know if their disappearance is suspicious or not."

The search is expected to resume over the coming weeks, weather permitting.