Former South Korean prime minister Han Myeong-sook speaks after being elected chairwoman of the liberal main opposition Democratic United Party, at the party's national convention held in Ilsan, South Korea, on Jan. 15, 2012. Han, a confidante to late former President Roh Moo-hyun, gained 24.5 percent of the vote from the 800,000-strong electoral college. She will now lead the party for two years. (Xinhua/Park Jin Hee)

Former South Korean prime minister Han Myeong-sook was elected chairwoman of the liberal main opposition Democratic United Party on Sunday.

Han, a confidante to late former President Roh Moo-hyun, gained 24.5 percent of the vote from the 800,000-strong electoral college. She will now lead the party for two years.

"I accept the chairmanship with a grave sense of responsibility," Han, 67, said after the result was announced. " With you, I will write a new chapter in the history of South Korea. "

Trailing behind her was Moon Sung-keun, a renowned actor and activist who led the "Power to the People" movement that was a driving force behind efforts to form a liberal coalition. A Roh loyalist, Moon won 16.7 percent of the ballots.

Park Young-sun, a reform-minded two-term lawmaker and former news anchorwoman, came in the third place with 15.7 percent.

Lee In-yeoung, Park Jie-won and Kim Boo-kyum also earned spots at the party's Supreme Council, a decision making body.

The leadership election was based on votes cast by party members, party delegates and ordinary citizens who had voluntarily signed up to cast their ballots.

The contest garnered an unparalleled amount of public attention, with more than 643,000 non-party members registering to vote, some 90 percent of them voting by mobile phone.

Some 127,000 party members also cast their votes, and 21,000 delegates voted during the convention.

Political observers have said the introduction of mobile voting, unprecedented in a party leadership election, has played a " revolutionary" role in encouraging mass participation.

The newly-formed party came into being late last year as a result of a merger between the Democratic Party, pro-Roh civic activists and trade unionists.

The coalition seeks to win a majority in the 299-member parliament, currently dominated by the ruling Grand National Party, by defeating conservative rivals in the April general election.

The new leadership faces another daunting task of winning a presidential election in December, as former ruling party leader Park Geun-hye leads pre-election surveys.

Sunday's election offered a glimpse into the upcoming parliamentary and presidential elections, with the nine liberals mounting a joint attack against President Lee Myung-bak and his conservative ruling party.

It is an opportune moment for the liberals, as the governing party, proved widely unpopular among young voters in recent elections, still struggles to shore up its image ahead of the polls this year.

The ruling party has been hit by a series of scandals, including allegations of a vote-buying attempt and an election-day hacking of the national election watchdog's website by ruling party aides.

"Once we win the general election and hold a parliamentary majority, we will lay bare the Lee Myung-bak administration's mismanagement (of state affairs) and corruption," Han said in her final speech before votes were counted.

She was recently acquitted of bribery-taking charges, which her supporters said were politically motivated.

Experts say Han's victory and the rising popularity of Moon signal a political comeback of pro-Roh forces, which will reshape the opposition political landscape.

Roh's 2009 suicide, which his followers blame on a politically motivated probe orchestrated under the Lee administration, has cast new lights on his political heirs.

Han served as the country's first female prime minister between 2006 and 2007 in the Roh administration. Moon, a political novice, was one of the vocal supporters of the late president.

The leadership race also showcased a growing influence of political fan clubs and social media.

Analysts say Moon's popularity among social media users and some 180,000 supporters behind his civic movement helped him secure the second place in the closely-watched election.

Han also vowed further efforts to facilitate online communications through social media.

Under the new leadership, the Democratic United Party is expected to form a task force this month to prepare for the April general election and start a process to nominate candidates for the December presidential election.