Leading figures in South Korea's main opposition Minjoo Party of Korea are squaring off over the deployment of an advanced U.S. missile defense system in the country, political observers said Wednesday.

"In terms of national interest, (the deployment) will bring more losses than gains," former party leader Moon Jae-in said. Moon is considered a leading opposition contender for the next presidential race slated for late 2017.

Last week, Seoul and Washington agreed to station the Terminal High Altitude Area Defense system in South Korea to better counter advances in Pyongyang's missile capability.

"The government's rushed move to deploy the THAAD cannot be understood, even taking the security issues into consideration," Moon said, adding the decision should win an approval from the parliament.

"The role of the government is to manage risks on the Korean Peninsula sparked by the North Korean nuke issues," Moon said. "The government failed in dealing with the THAAD issue, aggravating risks rather than solving issues."

Local pundits said the remark reflects the internal dispute within Minjoo, as Kim Chong-in, the interim head, has remained relatively neutral on the deployment.

Kim also expressed concerns over the THAAD deployment, he said that the party will not oppose the stationing.

On Wednesday, a group of lawmakers from Minjoo also made a separate statement against the THAAD.

"The deployment will deteriorate the inter-Korean issues, and weaken the international cooperation against the nuke problems," the statement said. "We are against the THAAD that will have an adverse impact on peace on the Korean Peninsula and in Northeast Asia."

Moon's remarks echo the stance of the People's Party and its leader, Rep. Ahn Cheol-soo, who is another contender vying to become the country's next president. (Yonhap)