The parliamentary spokesman of South Korea's main opposition party resigned under pressure Friday, taking responsibility for making what was perceived by critics as a disparaging remark against the family of President Park Geun-hye.

Citing a book he read, Rep. Hong Ihk-pyo, the parliamentary spokesman for the Democratic Party (DP), on Thursday called Park's father, former President Park Chung-hee, a "gwitae," or a "baby born to a ghost," meaning that he should not have been born.

The book, authored by a scholar in Japan, is about the former South Korean leader and former Japanese Prime Minister Nobusuke Kishi, the current Prime Minister Shinzo Abe's maternal grandfather who was once imprisoned as a Class-A war criminal.

"I extend my apologies for some inappropriate remarks I made and resign as the floor spokesman," Hong said during a news conference.

In his comments on the book on Thursday, Hong called Presidents Park and Abe "offsprings of gwitae" and claimed that both leaders are similar in that Abe is trying to revive Japanese militarism and Park appears to be dreaming of returning to the authoritarian rule of her father.

Park's father, who as an army major general seized power in a 1961 military coup, was assassinated by his intelligence chief in 1979. Supporters revere him as the man who has successfully rebuilt the war-ravaged South Korean economy, while detractors despise him as a dictator.

The presidential office Cheong Wa Dae bristled at Hong's remark, calling it an affront to the people who elected Park as president. On Friday, the ruling Saenuri Party asked Hong to resign as a lawmaker.

"The remark makes us question his qualification as a lawmaker.

It was verbal abuse and a slur that we can't even believe was made by a lawmaker representing the people," senior presidential press secretary Lee Jung-hyun said.

"This amounts to denying the legitimacy of a president chosen by the people and a direct challenge to liberal democracy," he said. "We ask if the spokesman's remark is the Democratic Party's official position. The opposition party should clearly state its position and apologize to the people and the president."

The controversy comes as the rival parties are bickering over whether the state spy agency, the National Intelligence Service (NIS), waged a smear campaign online against the opposition party in December's presidential election.

Park has disavowed any link to the spy agency's election meddling, stressing that she had no knowledge of the acts nor did she benefit from the alleged wrongdoing. But opposition lawmakers have accused her of being lukewarm about the scandal and even threatened to launch a campaign to nullify her election victory.

The ruling party on Friday canceled all its scheduled floor events for the day in protest of Hong's remark.

The rival parties had earlier agreed to visit the National Archives of Korea in Seongnam, south of Seoul, on Friday to select what could be controversial passages from a transcript of late President Roh Moo-hyun's 2007 summit meeting with then North Korean leader Kim Jong-il.

The excerpts would serve to verify claims by the ruling party that Roh tried to scrap a disputed Yellow Sea border with North Korea during the summit. The ruling party claims the late president undermined South Korea's sovereignty, while the opposition party insists the allegations are nonsensical and that they are aimed at diverting public attention away from the spy agency election scandal.

"How can the ruling and opposition parties meet and talk calmly in this situation?" Rep. Choi Kyoung-hwan, the floor leader of the ruling party, asked Yonhap News Agency by phone. "We are suspending our entire floor schedule and plan to discuss measures (to handle the situation)."

The DP expressed regret at the ruling party's move, saying it will press ahead with its floor schedule.

"The reason (the two parties agreed to) disclose the transcript was so that we could prevent further political strife and further division in public opinion," said Rep. Jung Sung-ho, the DP's first vice floor leader. "It's unacceptable that a ruling party with power and responsibilities has canceled it like this."

The DP will consider sending only its lawmakers to the state archives agency if the ruling party refuses to comply, he added.

(Yonhap News)