The disciplinary panel of South Korea’s Foreign Ministry decided to fire the diplomat, who was posted at its Washington embassy, according to Yonhap News Agency.
The diplomat, name withheld, had shared details of the May 7 phone call between Donald Trump and Moon Jae-in with Rep. Khang Hyo-shang, an opposition South Korean lawmaker of Liberty Korea Party (LKP).
The details made public include Moon’s request for Trump to visit Seoul after his Japan visit which concluded Monday and whether Trump had really approved South Korea's push for food aid to North Korea.
Kim In-chul, a spokesman for South Korean Foreign Ministry, told Yonhap that another official who shared a copy of the conversation with the diplomat would receive a penalty of three-month wage reduction.
"The diplomat acknowledged the wrongdoing but denied he had any intent to harm the government's policy,” the report said, Anadolu Agency reported.
Criminal complaints were filed against the diplomat and Khang over the leaking of a classified material.
Khang had in a press conference revealed details of the conversation earlier this month, accusing Moon of "begging" for Trump to visit South Korea.