There have been reports Leeds are seeking between $150,000 and $250,000 to release Buderus, who will be 34 by the time next season kicks off.
But Hetherington told the Newcastle Herald last night, "Our club have not placed any value on Danny Buderus and we have still had no contact at all from the Newcastle Knights club, or any of their officials."
Hetherington said Buderus remained "a key player" in the Rhinos' plans for next season.
"He's under contract and that's the situation," Hetherington said.
"There seems to be a lot of speculation and comment and it's quite unfounded, because as I said there has been no dialogue between the clubs."
Buderus's agent, George Mimis, has been in England for talks with Leeds, and Knights officials hope to speak with him this week.