Democrat Sukhumbhand Paribatra quoted Cambodian Commerce Minister Cham Prasidh as saying in the Cambodia Daily that Thailand had linked negotiations on territorial waters with the disputed temple.
"What the Cambodian minister said contradicts Prime Minister Samak Sundaravej, who said there is no linkage between the two issues, so why does the ministry not protest to the Cambodians over the allegation?" he said.
Sukhumbhand did not indicate how the two issues were linked.
News commentators have accused the government of trading off land below the temple for an oil and gas concession for former prime minister Thaksin Shinawatra.
"There is a huge interest in the overlapping area. The Foreign Ministry should handle the case with care, and not allow any private investors to get involved," said Sukhumbhand, a former deputy foreign minister. Noppadon said nobody in his government could exchange the Preah Vihear land for an oil and gas concession in the overlapping maritime area.
Preah Vihear came before the International Court of Justice in 1962. It ruled the temple belonged to Cambodia. The dispute was rekindled last year when Phnom Penh sought listing for the Hindu temple as a world heritage. Thailand opposed the proposal as Cambodia had annexed the surrounding land over which Thailand claims sovereignty.
"Negotiations are still going on and the two sides should be able to reach common ground within two weeks," Noppadon said.
Cambodia's Deputy Prime Minister Sok An, who is in charge of the matter, will dispatch experts to wrap up the issue with Thai officials next week. Preah Vihear and the maritime boundary are completely separate issues and could not be linked, Noppadon said.