SEOUL, Korea, Republic Of - Hundreds of flights have been cancelled in South Korea while North Korea's leader expressed concern about a potential loss of lives and crops as the countries brace for a strong typhoon.

Packing a maximum wind speed of 155 kilometres (96 miles) per hour, Typhoon Bavi is already lashing South Korea's southern resort island of Jeju, toppling trees, flooding roads and ripping off signboards as it passes over waters off the island's western shores.

There are no immediate reports of injuries.

South Korea's weather agency says the typhoon will start to affect the mainland at night before making landfall in western North Korea early Thursday.

In Seoul, workers dismantled some makeshift coronavirus testing stations over worries that the tents and booths might not withstand strong winds.