Floor leaders of South Korea's ruling Saenuri Party offered to step down en masse Wednesday after the parliament voted down the prosecutors' request to arrest a fellow lawmaker.

Only 74 out of 271 lawmakers voted for the arrest motion for Chung Doo-un, a three-term legislator suspected of receiving kickbacks from a local savings bank.

Courts here need legislative approval for arresting a lawmaker when the parliament is in session, but the ruling party had vowed to voluntarily give up on the privilege of immunity as part of reform efforts.

Shortly after the parliament vetoed the arrest motion, Saenuri floor leader Lee Han-koo offered an apology for letting down the public awaiting the pledged parliamentary reforms.

The 55-year-old Chung, known for his close ties to President Lee Myung-bak, allegedly took bribes from the head of Solomon Savings Bank before Lee won the 2007 presidential election.

The bank chairman, Lim Suk, is now jailed in an escalating bribery scandal that has led to the imprisonment of the president' s elder brother Lee Sang-deuk.