Prosecutors sought a detention warrant Monday for the floor leader of the main opposition Democratic United Party (DUP) over bribery suspicions, setting in motion a potential showdown between rival parties over whether the parliament should consent to his arrest.

The move came after Rep. Park Jie-won three times snubbed summons to appear before the prosecution for questioning on allegations he received money from ailing savings banks that sought his influence to avoid shutdown.

Park has denied the allegations, claiming the investigation is politically motivated.

Park's detention requires parliamentary consent as lawmakers in South Korea are immune from arrest while the National Assembly is in session. The DUP and the ruling Saenuri Party are expected to clash over the issue.

Park said earlier Monday he is "contemplating what course of action he should take."

The National Assembly is expected to table an arrest motion for Park at a plenary session Wednesday. The motion needs to be put to a vote within 72 hours, with a majority of votes needed for its approval.

The ruling Saenuri Party, which has 149 seats in the 300-member parliament, reportedly set a policy to approve a motion to arrest Park if the motion is put to a vote, party officials said.

Park "should voluntarily present himself to prosecutors and undergo questioning," party spokesman Hong il-pyo told reporters.

Meanwhile, the DUP claimed the prosecutors' move is designed to water down suspicions over illegal campaign funding involving former aides of President Lee Myung-bak ahead of the 2007 presidential election.

"We will fight against oppression of the opposition party," party spokesman Jung Sung-ho told reporters, without elaborating on how they would thwart the arrest motion.

Such an arrest motion is a politically sensitive issue in South Korea. Earlier this month, the ruling party came under intense fire after the National Assembly struck down an arrest motion for one of its lawmakers, Rep. Chung Doo-un, who was also accused of bribery.

The party's rejection of the arrest motion for its fellow lawmaker was seen as a slap in the face of voters as it ran counter to the ruling party's promise to forgo privileges granted to legislators, including the immunity from arrest.

"(The prosecution) will again seek an arrest warrant for Park if the parliament rejects the arrest motion," a prosecution official close to the investigation said, adding that they intend to once again seek a detention warrant for Chung when the current parliamentary session is over.

Park, a three-term lawmaker, is suspected of accepting around 100 million won ($87,657) in kickbacks from the now-jailed Solomon Savings Bank chairman Lim Suk in return for influence peddling on behalf of the savings bank before the general elections in 2008, according to the prosecutors.

Park was indicted in 2003 on charges of taking slush funds from Hyundai Group right before the historic inter-Korean summit in 2000, but was cleared of the charges by the Supreme Court.

He was also sentenced to 3 years in jail for receiving kickbacks from several local conglomerates and released from prison under a special pardon in 2006.

In the savings bank scandal, an elder brother of President Lee has also been indicted on bribery charges. It is the first time in South Korea a brother of a sitting president has been arrested to stand trial. (Yonhap)