South Korea's ruling party on Saturday demanded again that National Assembly Speaker Chung Sye-kyun offer a public apology for his remarks on the planned deployment of a U.S. missile defense system here.

The Saenuri Party claimed he breached the obligation of maintaining political neutrality as the leader of the parliament.

Delivering a speech Thursday to open the regular parliamentary session, Chung criticized the government's decision to allow the U.S. military to position the Terminal High Altitude Area Defense system on the peninsula.

Chung, a six-term lawmaker, is from the main opposition Minjoo Party of Korea which is staunchly opposed to a THAAD battery in South Korea.

In protest, the ruling party, officially supportive of the deployment plan, announced a boycott of all National Assembly sessions.

The parties, nonetheless, managed to hold a regular meeting late Friday to pass the extra budget bill, with vice speaker Park Joo-sun of the minor People’s Party chairing it on behalf of Chung.

"We are glad that the extra budget plan was finally passed," Saenuri said in a statement.

The ruling party argued that Chung should be held responsible for the delay in passing the budget bill, as he failed to maintain political neutrality. He was also negligent in mediating between the different opinions of the parties, it added.

"The extra budget plan passed on Friday's session was merely a start for the functioning parliament," Saenuri spokesman Min Kyung-wook said, adding Chung must make a sincere apology to theruling party.

Chung earlier said he "wishes to express an apology to the people," but declined to make any related direct statement for Saenuri. (Yonhap)