"We've decided to open the National Assembly. We will submit a request to convene the National Assembly today," LKP floor leader Na Kyung-won told a press conference.

"As a responsible opposition party, we've made the decision because we have nothing to expect from the ruling Democratic Party," she added.

Earlier in the day, the floor leaders of the DP and two opposition parties met but failed to reach an agreement to normalize the parliament.

"We'll do our best for the swift passage of bills on the economy and various reforms in a March session," DP floor leader Hong Young-pyo told reporters.

The National Assembly is supposed to open an extraordinary session in March to deal with scores of pending bills, mostly related to the economy, labor and inter-Korean affairs.

But hurdles for the smooth operation of the March session remain as the parties differ on major issues, such as how to handle allegations of real estate speculation by Rep. Sohn Hye-won.

The LKP has called for a parliamentary probe into Sohn, who left the ruling party in January as she fought conservatives' various attacks, including an allegation that she, along with relatives and aides, made speculative real estate purchases in Mokpo, 410 kilometers southwest of Seoul, now a cultural heritage district. Sohn said they bought run-down buildings with historic values to protect them against developers. 

The ruling party demanded the parliamentary probe be expanded to other conflict of interest cases, some involving LKP lawmakers.

The parties also sparred over the presidential office Cheong Wa Dae's alleged abuse of power and surveillance of civilians.

A former government official, who claims to be a public interest whistleblower, alleged in December that the presidential office exerted inappropriate influence on the country's tobacco maker and the finance ministry.

An ex-special inspector also made allegations that Cheong Wa Dae ordered him to spy on civilians while he worked at the office.

President Moon Jae-in's office flatly denied the allegations. (Yonhap)