A powerful typhoon that officials warned could bring record rains and gusts strong enough to flip cars slammed into southern Japan on Sunday, prompting authorities to urge millions to seek shelter.

Typhoon Haishen has weakened somewhat as it neared Japan's mainland, and shifted further west out to sea, but it remained a "large" and "extremely strong" storm.

After lashing a string of exposed, remote southern islands, it neared Japan's Kyushu region on Sunday evening, with authorities issuing evacuation advisories for more than seven million residents.

The weather agency urged people to exercise "most serious caution" for possible record rain, violent winds, high waves and surging tides.

"Record-level rainfall is expected. It may cause landslides or it could cause even large rivers to flood," said Yoshihisa Nakamoto, director of the forecast division at the Japan Meteorological Agency, during a televised briefing.

He added that surging tides could cause widespread flooding in low-lying areas, particularly around river mouths.

As the storm passed over several remote islands earlier Sunday, strong winds bent palm trees and sheets of rain lashed the area.

At an emergency cabinet meeting, Prime Minister Shinzo Abe warned that flooding and landslides were a possibility.

"Maximum caution is needed as record rain, violent winds, high waves and high tides are possible," he said.

"I ask the Japanese people, including those who live in high-risk areas for flooding rivers or high tides, to stay informed and take action immediately to ensure their safety."

At 10 pm (1300 GMT), Haishen was located about 90 kilometres (56 miles) west of Makurazaki city, packing gusts up to 216 kmh (135 miles) -- strong enough to overturn vehicles and snap wooden power poles.

The storm was forecast to move north and travel off the western coast of Kyushu before reaching the Korean peninsula Monday morning, according to the weather agency.

It comes as North Korea reels from severe damage left by a recent typhoon.

Leader Kim Jong Un appeared in state media over the weekend to inspect the damage and ordered 12,000 elite members of his ruling party to help with recovery efforts.

- Evacuation orders, blackouts -

Japanese authorities issued evacuation orders for 1.8 million people in the affected area, with 5.6 million people issued lower-level advisories, national broadcaster NHK said.

Evacuation orders in Japan are not compulsory, though authorities strongly urge people to follow them.

Local officials asked individuals to avoid crowded shelters where possible, to reduce the risk of coronavirus infections, and some centres were forced to turn people away in order to have enough space to maintain social distancing.

In some places, residents were checking into nearby hotels to comply with evacuations advisories.

Hotel Polaris in Shibushi city, Kagoshima, said all 73 of its rooms were sold out for the weekend.

"This is a large building for our area. I think our guests have chosen to stay with us to feel safe," front desk employee Takayuki Shinmura told AFP, adding that it was unusual for all of the hotel's rooms to be occupied during typhoons.

Those who sought hotel rooms said the pandemic and discomfort of public shelters were weighing on them.

"I am worried about coronavirus infections. We're with small children too, so we did not want other people to see us as big trouble," an elderly man in Shibushi city told NHK after checking in at a local hotel with seven relatives.

The storm has forced the cancellation of nearly 550 flights and disrupted train services, NHK said.

Many factories also suspended operations, including three plants operated by Toyota.

More than 220,000 homes in the Kyushu region lost power Sunday evening as the storm swept just west of the region.

Haishen forced the Japanese coast guard to suspend its search for dozens of missing sailors from the Gulf Livestock 1 cargo ship that sank in an earlier storm.

Two survivors and the body of a third crew member were found before the search was suspended, and the coast guard said it will resume the operation when Haishen clears the region.