Victoria Police said the dogs had previously assisted in looking for the pair, who had not been seen since March 2020.

"Missing Persons Squad detectives, with the assistance of specialist police, have conducted numerous searches in and around the Wonnangatta Valley over the last 12 months, however Russell and Carol have not been located," police said in a statement.

"Investigators are also continuing to appeal to anyone who was in the Wonnangatta area around that time, including campers, 4x4 day trippers, hunters, fishermen or trail bike riders, regardless of whether they saw or heard anything.

"Detectives are also keen to speak to anyone who was in the area of Howitt Plains and Zeka Spur Track on 19 or 20 March, and the Wonnangatta Valley and Wonnangatta Station between 20-24 March who has not yet made contact with police is urged to come forward."

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Detectives have also established that Mr Hill was camping alone with his Landcruiser in the area of the King Billy and Bluff Track between March 11-13, 2020.

Police are keen to speak to anyone in that area on those dates.

Information was later received about sighting of an older person or pair in the Black Snake Creek, Eaglevale River crossing and the Ollies Jump area on March 22-23, however police have never been able to establish if this was the missing campers.

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Detectives call for anyone in this area, any older couple who may be these persons, to also come forward.

Detective Acting Inspector Anthony Combridge, officer in charge of the Missing Persons Squad, said police remained committed to finding answers about what happened to the campers.

"We will continue to search the area and encourage anyone with information to come forward, no matter how small they think that information might be," he said.

Anyone who sees Mr Hill or Ms Clay should ring triple zero while anyone with any other information regarding their disappearance or who has any CCTV or dashcam footage should contact Crime Stoppers on 1800 333 000 or crimestoppersvic.com.au.

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