SEOUL, Nov. 28 (Yonhap) -- Minor parties on Wednesday called on bigger rivals to immediately join a push for adopting a new proportional representation system as they seek to reform the parliamentary electoral scheme.

The ruling Democratic Party (DP) and the main opposition Liberty Korea Party (LKP) remain lukewarm toward minor parties' call to introduce the German-style mixed-member proportional (MMP) representation system.

Under MMP representation, the number of parliamentary seats that each party receives is tied to the percentage of voters' support for parties.

Minor parties are hoping to increase their presence in the National Assembly, traditionally dominated by the two major parties, with a new election system that would help boost their representation.

The chiefs, floor leaders and officials from the minor conservative Bareunmirae Party (BP), the liberal Party for Democracy and Peace (PDP) and the leftist Justice Party made a joint call for the two parties to adopt the electoral reform.

"The parties should lay down their vested rights and immediately accept a proposal to adopt the MMP representation system," the parties said in a joint statement.

South Korea has a single-member district system, which critics say generates many dead votes and falls short of representing voters' various voices.

In 2004, the country also introduced proportional representation, allowing a voter to cast two ballots for parliamentary elections.

One ballot is cast to pick a single representative for each district and the other to pick a party for proportional representation, which currently makes up for 15.7 percent of the total parliamentary seats.

Sohn Hak-kyu, the chairman of the BP, stressed that the major parties should heed the people's call for the genuine political reform.

"President Moon Jae-in and DP chairman Lee Hae-chan are aware that the adoption of the MMP representation system is unavoidable. They also said so. But now they are all shunning it," Sohn said.

In his election campaign, President Moon promised to reform the parliamentary election system in a way that will enhance representation. He also in August raised the need to revise the country's election law when he agreed with rival parties' floor leaders to form a joint policy consultation body in what the president calls joint governance.

Hong Young-pyo, the ruling DP's floor leader, told a radio program that Moon has a strong will to reform the electoral system.

"When I went to the airport Tuesday (to see him off), President Moon said that South Korea should overhaul the election system this time," Hong added.

Moon left the country Tuesday on a three-nation tour that will take him to Argentina for the annual Group of 20 summit.

The presidential office, Cheong Wa Dae, appeared to seek to distance itself from the issue, saying that electoral reform is a matter that should be handled by the legislative body.

"(President Moon) thinks that the electoral reform should be carried out in a way that will strengthen representation," a presidential official said.

"But for now, it is right for the National Assembly to discuss the issue," he said, when asked over whether Cheong Wa Dae has a plan to join the consultation.

One of the most contentious issues is whether the number of parliamentary seats, which stands at 300 at maximum, will be increased under the MMP representation.

"Whether to increase the number of lawmakers should be first settled" Hong said Tuesday in response to criticism on his party that the DP backpedaled from its support for the MMP system.

"Most people oppose it and the main opposition LKP said that it will not allow even one seat to be added," he said.

Source: Yonhap News Agency