SEOUL, South Korea (AP) - South Korea's justice minister resigned Monday, citing the political burden of an investigation into alleged financial crimes and academic favors surrounding his family, a scandal that has rocked Seoul's liberal government and spurred huge protests.

Cho Kuk has denied wrongdoing. But the law professor who for years cultivated an anti-elitist reformist image said he couldn't remain a government minister while ignoring the pain his family was enduring.

Huge crowds of Cho's supporters and critics have marched in South Korea's capital in recent weeks, demonstrating how the months-long saga over Cho has deepened the country's political divide.

Cho said in a statement he was offering to resign to reduce the burden on President Moon Jae-in, whose office later said he accepted Cho's offer.

Cho's resignation came as state prosecutors continued a criminal investigation into his university professor wife, brother and other relatives over allegations of dubious financial investments, fraud and fake credentials for his daughter that may have helped her enter a top university in Seoul and a medical school in Busan.

"I concluded that I should no longer burden the president and the government with issues surrounding my family," Cho said in an emailed statement. "I think the time has come that the completion of efforts to reform the prosecution would only be possible if I step down from my position."

Moon's liberal Minjoo Party and Cho's supporters, who occupied streets in front of a Seoul prosecutors office for the fourth-straight weekend Saturday, have claimed the investigation is aimed at intimating Cho, who has pushed for reforms that include curbing the power of prosecutors.

South Korea's main opposition party called Cho's resignation offer "too late" and criticized Moon for causing turmoil with a divisive appointment.

In a meeting with senior aides, Moon said he was "very sorry for consequentially creating a lot of conflict between the people" over his hand-picked choice but also praised Cho's "passion for prosecutorial reform and willingness to calmly withstand various difficulties to get it done."

Moon had stood firmly by Cho, whom he appointed a month ago despite parliamentary resistance.

But the controversy dented the popularity of Moon and his ruling liberal party in recent polls, an alarming development for the liberals ahead of parliamentary elections in April.

The conservative Liberty Korea Party criticized Moon for sticking with Cho for too long.

"Is President Moon Jae-in listening to people's voices only after his and his ruling party's approval ratings face the danger of a nosedive?" the conservative Liberty Korea Party said in a statement.

In South Korea, prosecutors have exclusive authority to indict and seek warrants for criminal suspects and exercise control over police investigative activities. They can also directly initiate criminal investigations even when there's no complaint.

Critics say such powers are excessive and have prompted past conservative governments to use the prosecution as a political tool to suppress opponents and carry out vendettas.

The controversy over Cho has struck a nerve in a country facing widening inequality and brutally competitive school environments and has tarnished the image of Moon, who vowed to restore faith in fairness and justice after replacing President Park Geun-hye, who was impeached and jailed for corruption.

Recent polls indicate Moon's popularity has sank to the lowest levels since he took office. In a survey of some 1,000 South Koreans released last Friday by Gallup Korea, 51% of the respondents negatively rated Moon's performance in state affairs, compared to 43% who said he was doing a good job. The survey's margin of error was plus or minus 3.1 percentage points.

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Associated Press writer Hyung-jin Kim contributed to this report.

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