BANGKOK — Thailand’s prime minister, Paetongtarn Shinawatra, is facing mounting pressure to resign after she appeared to disparage her country’s powerful military and to take a deferential tone in a private conversation with the de facto leader of Cambodia.

That talk was supposed to tamp down tensions over a border dispute with Cambodia that has been simmering for weeks. Instead, it has unleashed new turmoil in Thailand, which in recent years has reeled from one political crisis after another.

On Sunday, Paetongtarn discussed the border issue with Hun Sen, the former prime minister of Cambodia and the father of the current leader.

Hun Sen posted a recording of their conversation — conducted with Thai and Khmer language interpreters — on his Facebook page Wednesday.

In the recording, she is heard addressing Hun Sen, who remains head of the ruling Cambodian People’s Party, as “uncle” in English. She also urged him to ignore “the opposite side,” a reference to the Thai military, which she said was trying to look “cool” by making statements that were not beneficial.

“Tell him that actually if he wants something, he can say it and we will arrange it for him,” Paetongtarn, referring to Hun Sen, says to the Thai interpreter.

Her comments drew condemnation from lawmakers, both those in her coalition and in the opposition, who all called on Paetongtarn to resign.

The conversation has become the latest focus for a growing dissatisfaction with Paetongtarn’s government and her family.