Hundreds of flights and high-speed trains were cancelled and businesses shuttered in the South Korean port town of Busan after Tropical Storm Khanun made landfall Thursday, bringing heavy rain and high winds.

The storm, which battered Japan before taking a circuitous route towards the Korean peninsula, made landfall at around 9:20 am local time (0020 GMT) in the south, and is set to travel northwards, bringing heavy rain nationwide, Korea's meteorological agency said.

More than 10,000 people have been evacuated, with Prime Minister Han Duck-soo urging local governments to "verify whether residents in high-risk areas have failed to evacuate," and if so, to ensure they do.

Typhoon warnings have been issued nationwide, with downpours of up to 500 millimetres forecast in northeastern coastal areas and 100 to 200 millimetres in Seoul and its surrounding areas until early Friday.

Busan was hit by strong winds, with pedestrians struggling to walk in gusts blowing as fast as around 145 kilometres per hour. Many stores and cafes were closed.

At least 330 flights were cancelled as of Thursday, and sea routes and railways closed, officials said.

The typhoon had already prompted the evacuation of tens of thousands of scouts from their jamboree campsite in the south of the country earlier this week.

In Japan, the storm prompted some districts in the country's southern Miyazaki region to issue its highest-level alert overnight, urging residents to "protect their lives immediately" as the risk of rain-triggered mudslides increased.

Lower-level evacuation advisories were also issued in parts of Ehime, Kochi and Oita regions, according to NHK.

As of 9:00 am Thursday, more than 10,000 households on the island of Kyushu remained without power due to the storm.

Japan Airlines and All Nippon Airways cancelled about 80 flights in total for Thursday, spokeswomen told AFP.

The South Korean government has asked the public to "refrain from going outside and remain safely inside until the typhoon passes", according to the interior ministry.

More than 40 people have been killed by flooding and landslides in South Korea during monsoon rains this year, including one incident where vehicles were trapped in an underground tunnel by flash floods.

The country also endured record-breaking rains and flooding last year, which left more than 11 people dead.

They included three people who died trapped in a Seoul basement apartment of the kind that became internationally known because of the Oscar-winning Korean film "Parasite".

The government said at the time that the 2022 flooding was the heaviest rainfall since records began 115 years ago, blaming climate change for the extreme weather.