South Korea's parliamentary speaker Park Hee-tae announced his exit on Thursday amid allegations he attempted to bribe his way to the chairmanship of the ruling party in 2008.

"I feel responsible for the problems involving myself and intend to resign," Park said in a statement read by parliamentary spokesman Han Jong-tae.

"Please let me be held responsible when others are found to have been involved in the scandal," Park said in the statement.

Park has been under pressure to resign after Koh Seung-duk of the ruling Saenuri Party, formerly the Grand National Party, claimed Park's aide offered him an envelope containing three million won (2,688 U.S. dollars) in an attempt to buy his vote before the party leadership contest.

Park, who has denied his involvement in the alleged vote-buying scandal, was elected head of the conservative ruling party after the 2008 convention.

The scandal has been a blow to the ruling party, which struggles to recover from election defeats and rejuvenate itself before key polls this year.

Park is expected to be summoned by prosecutors for questioning.