Subway stations and major roads were underwater in the South Korean capital Seoul after record-breaking rains caused severe flooding, with at least seven people dead and seven more missing, officials said Tuesday.

Dramatic images shared on social media late Monday showed people wading through waist-deep water, metro stations overflowing, and cars half-submerged in Seoul's posh Gangnam district after torrential rain battered the city.

The downpour that began Monday is the heaviest rainfall in South Korea in 80 years, according to Seoul's Yonhap news agency.

"At least seven people died in the Seoul metropolitan area, while seven others are missing, due to heavy rain as of 7:30 this morning," an official at Seoul's Interior ministry told AFP.

Local reports said three people living in a banjiha -- cramped basement flats of the kind made famous in Bong Joon-ho's Oscar-winning "Parasite" -- including a teenager, died as their apartment was inundated by floodwaters.

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Rainfall that caused flooding in Seoul over Monday and Tuesday was the heaviest the country had seen in 80 years / © YONHAP/AFP

Parts of Seoul, surrounding Gyeonggi province and port city Incheon recorded rains of more than 100 millimeters per hour Monday night, according to the Yonhap news agency, with per-hour precipitation in the capital's Dongjak district surpassing 141.5 mm at one point, the heaviest downpour since 1942.

President Yoon Suk-yeol ordered government officials to evacuate residents from high-risk areas and encouraged businesses to allow employees flexible commuting hours on Tuesday morning.

"Nothing is more precious than life and safety. The government will thoroughly manage the heavy rain situation," he wrote on his Facebook account.

Neighbourhoods close to the presidential residence in southern Seoul were affected, according to images of the flooding posted on social media.

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At least seven people were killed and another seven missing after a night of massive rainfall in Seoul / © YONHAP/AFP

Power outages were reported across the capital area late Monday, while some operation of the Seoul metro as well as railway services was temporarily disrupted by the heavy rain.

The Seoul express bus terminal in Gangnam was submerged, and flood water also leaked into a cafe and library at the COEX Convention and Exhibition Center in the same area.

An image of a man in a suit sitting on the hood of a submerged vehicle in the wealthy district in southern Seoul -- which was featured in Psy's 2012 K-pop hit "Gangnam Style" -- went viral online.

South Korea remained highly disrupted Tuesday, with many roads and tunnels closed for safety reasons, Yonhap reported.

Hiking trails at many of South Korea's national parks were closed and passenger ferry routes, including from Incheon port, were suspended.