SEOUL • South Korean President Moon Jae-in's support rate hit a record low as turmoil over the fate of the country's top prosecutor rocked his government, in a worrisome sign as he enters the latter stages of his administration.

Mr Moon's approval rating fell to 37.4 per cent, down from 43.8 per cent a week ago, a tracking survey from Realmeter released yesterday showed.

The drop comes as his government has tried to oust Mr Yoon Seok-youl from office after the chief prosecutor launched probes into suspected graft by members of Mr Moon's inner circle.

The poll also showed troubling signs for Mr Moon's progressive camp, which saw its support rate slip and be overtaken for the first time in about four months by the conservative faction.

This comes as Mr Moon's single, five-year term ends in 2022 and conservatives are looking to take back the presidential Blue House.

Mr Yoon has drawn the ire of Justice Minister Choo Mi-ae, who has accused him of thwarting the President's attempts at reform.

The prosecutor-general has launched a probe into suspected nepotism by Ms Choo, looking into whether she inappropriately helped her son extend his medical leave from military service - a charge the Justice Minister denies.

The poll showed a sharp drop in support among liberal and swing voters, which could make it difficult for members of Mr Moon's progressive camp to ride his coattails in a presidential race.

The public appears to be siding with Mr Yoon in the fight, with the long-time prosecutor emerging in recent weeks as a top contender for the presidency.

The fight has come as Mr Moon faces criticism from many in the public for what they see as a failure to deliver on his pledges to cool a red-hot real estate market and decrease income inequality.

The authority of prosecutors has been a sore spot in South Korea for years, and limiting prosecutors' investigative powers has been one of Mr Moon's key policy objectives since taking office in May 2017.

Although the prosecutors pledge independence, they have faced criticism from the left and right for using prosecutorial powers for political purposes and for protecting the privileged.

Mr Yoon is facing a disciplinary hearing today, after winning an injunction from a Seoul court this week that blocked his suspension.

He has requested that the hearing be delayed.

After the committee's decision, Mr Moon will decide on disciplinary action.

Mr Yoon was handpicked by the President as the country's top prosecutor last year, with a mandate to make good on Mr Moon's pledges to clean up the government and go after the most powerful.

But soon after taking office, Mr Yoon focused his attention on Mr Moon's pick at that time to lead the Justice Ministry - Mr Cho Kuk.

A close aide to Mr Moon, Mr Cho was indicted on a dozen charges, including bribery.

Mr Cho, who was forced from office, has denied the charges.

The scandal sent Mr Moon's support rate to its previous all-time low.

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