SEOUL (REUTERS) - South Korean President Moon Jae-in on Monday (March 29) fired his top economic policy adviser for raising the rent on an apartment he owns in Seoul's affluent Gangnam district amid public furore over skyrocketing home prices.

Mr Kim Sang-jo raised the rent by about 14 per cent in July, two days before a 5 per cent cap on rent increases took effect as part of government efforts to protect tenants from unreasonable hikes.

"I am very sorry that I've disappointed the people at this grave time when we should be making all-out efforts to root out real estate speculation," Mr Kim told a briefing.

Mr Kim had served the president since Mr Moon took office in May 2017, first as antitrust chief and then chief policy adviser.

He was replaced with Mr Lee Ho-seung, Mr Moon's senior economic secretary, Mr Moon's chief of staff told a briefing.

Home prices in Seoul have shot up more than 50 per cent since 2017, the fastest pace in the world, according to statistics site Numbeo.

The uproar over housing affordability intensified earlier this month after employees of a state housing developer were accused of insider trading in land.

The issue has taken a toll on Mr Moon's approval ratings, which hit record lows this month, and is hurting support for his Democratic Party ahead of a by-election next month to pick the mayors of the country's two largest cities, Seoul and Busan.

Mr Moon called for a broader, thorough investigation into all allegations, and measures to eradicate property speculation, including a law prohibiting conflicts of interest involving public servants.

"We have to take people's anger and reproach seriously," he told a meeting on anti-corruption policy.

"Their anger is touching on more fundamental problems, including massive unearned incomes, widening inequality, fading dreams of having their own home and a new class society."