South Korea's ruling Liberty Korea Party on Wednesday urged the government to expand protection for a former North Korean embassy minister posted to London who defected to Seoul last year, after reports showed North Korean leader's half brother was killed in Malaysia.

"Acting President and Prime Minister Hwang Kyo-ahn and the government must keep a watchful eye on North Korea's movements," Rep. Chung Woo-taik, the floor leader of the Liberty Korea Party, said. "We also must bolster protection of defectors including Thae Yong-ho, who was Pyongyang's No. 2 diplomat to Britain."

The remark came as Kim Jong-nam was apparently assassinated on Monday at an airport in Malaysia.

"It is extremely shocking, and shows the cruelty and depravity of the North Korean regime," Chung said. "Related authorities should gather information and focus every effort to protect defectors in the country."

Chung also criticized Moon Jae-in, a potential presidential hopeful from the main opposition Democratic Party for protesting the deployment of an advanced US missile defense system in the country.

"We would like to ask again if Moon is qualified to run for the presidency when he has openly protested against the Terminal High Altitude Area Defense system without any alternative plan," Chung said.

Chung said the Liberty Korea Party will cooperate with the government to facilitate the prompt deployment of the THAAD battery.

The allies agreed in July to have a THAAD battery in the country by end of 2017.

"Regardless of the presidential election and domestic politics, parties should cooperate in coping with the changing environment on security," Chung said, urging opposition parties to establish a clear stance on the US missile shield. (Yonhap)