Park Geun-hye, South Korea's ruling Saenuri Party's presidential candidate, bows before a news conference at the main office of the party in Seoul, Sept 24, 2012. [Photo/Agencies]

SEOUL - Park Geun-hye, the daughter of South Korea's former military strongman Park Chung-hee, offered a public apology Monday to the victims of her father's 18-year rule as her approval ratings headed south ahead of the December presidential election.

Park, the presidential candidate of the conservative ruling Saenuri Party, had hitherto been reluctant to offer an outright apology and defended her father's 1961 military coup as an " inevitable" decision that helped modernize the country.

Her view on the late dictator's controversial legacy, which is still subject to fierce partisan debates here, was attributed to a sudden decline in her poll ratings just as her liberal rivals were gaining traction.

"I offer a sincere apology to those who suffered," the 60-year-old said in a press conference, apologizing for the coup, the 1972 constitutional amendment that strengthened Park Chung-hee's iron grip on power and the "Inhyukdang" incident that led to the infamous execution of dissidents.

"(The incidents) violated the constitutional values and delayed political progress," said Park, who remains widely popular among conservatives and old-timers nostalgic for the country's rags-to- riches economic rise under the senior Park's rule.

The first woman to clinch a presidential nomination from a major political party, Park said she will establish a committee tasked with shedding light on historical issues for national unity.

The presidential election will be held on Dec 19. The incumbent President Lee Myung-bak, who defeated Park in the 2007 presidential race, is barred by constitution from re-election.

Her rivals are the main opposition Democratic United Party's presidential candidate Moon Jae-in, who was jailed for protesting against her father's military rule in the 1970's and popular entrepreneur-turned-professor Ahn Cheol-soo.