Record rains have left a muddy aftermath in a Seoul university after lashing the South Korean capital on Monday night.

Footage shows the destruction caused by the unprecedented downpour on Seoul National University in the Gwanak District in the capital Seoul on Wednesday, August 10, with piles of mud and branches scattered around the storm-battered campus.

Trees were uprooted by the deluge, which also entered some of the university's buildings, student Kim Harold Peji said.

Korea's Interior and Safety Ministry said at least nine were killed, while 17 others were injured. At least seven people are still missing, the agency added.

Parts of Seoul recorded up to 19.6 inches of rainfall on Monday, at one point reaching 5.6 inches of rain per hour - reportedly the highest rate measured in the city in 80 years.

South Korean president Yoon Suk-yeol has ordered the evacuation of residents from high-risk areas as the Korean Meteorological Agency expects heavy rains to continue battering the capital city until Wednesday.