The prosecution is likely to summon National Assembly Speaker Park Hee-tae as early as next week to investigate whether he attempted to buy votes during the ruling party’s chairmanship election in 2008.

Investigators are also expanding their investigation to verify whether more lawmakers are involved in the irregularities that could put the perpetrator behind bars for more than five years.

According to the Seoul Central Prosecutors’ Office, Rep. Koh Seung-duk of the ruling Grand National Party attended the prosecutors’ questioning on Saturday through Sunday and said it was Park that tried to bribe him for the July 3, 2008 chairman election.

Koh has reportedly said that one of his office workers had received an envelope about two to three days before the election from a “young man with glasses” at his office. In it were three bundles of 1 million won ($869) in 10,000 won notes and one of Park’s name cards. Koh ordered his assistant to return the money a day after the election, he alleged.

“I heard the man had a bag full of envelops like that,” Koh said at a press briefing Monday. “My revelation is to stem illegalities rampant in the party,” he said.

On Monday, the prosecutors summoned Kim, the assistant ordered to return the money, and the receptionist who received the envelop at Koh’s office. The investigators also said they will call in a former assistant to Park to verify the testimony. The assistant has told reporters that he had worked for Park during the election but does not remember anything about the bribery.

Another allegation was raised about a mid-ranking GNP official who ordered GNP district council members to distribute 500,000 won to 30 local GNP office operators in Seoul on behalf of Park during the 2008 election.

“Currently we are focusing on verifying Koh’s claims but we are also studying whether more people are involved,” a prosecutor said.

Park, who is now on a tour around Japan, Uzbekistan, Azerbaijan and Sri Lanka, denied the allegations.

“I heard about the claims and did some research but could not find a single person in my office who delivered bribes. Moreover, I had no name card to deliver at that time,” he told reporters at a hotel in Tokyo on Monday.

“Koh should be more specific about who gave what to him,” he said. If he is to be questioned, it will be no sooner than next week when he returns, observers said.

Prosecutors are also planning to launch another investigation into allegations that a similar cash-for-vote scheme was conducted around the 2010 GNP leadership election.

“We are considering asking the ruling party to conduct internal study ahead,” a prosecutor was quoted as saying to a local daily.

By Bae Ji-sook (baejisook@heraldcorp.com)