Tokyo - Rugby World Cup officials defended their contingency planning and urged fans to stay safe as Typhoon Hagibis, which has already caused two games to be cancelled, ploughed towards Japan on Saturday bringing potentially record rainfall.

Governing body World Rugby told fans to stay indoors and follow any evacuation orders as the unusually large storm, expected to whip up "brutal winds and violent seas", churned towards Tokyo.

Thousands of foreign supporters are in Japan for the first World Cup held in Asia, which has been badly disrupted by Hagibis - on track to be the strongest storm to hit Japan in decades.

"Remain indoors, check typhoon-related updates regularly and follow the advice of local authorities including any evacuation orders and ensure you have basic food provisions," World Rugby warned.

"Keep travel documents and essential medication with you in case you have to move at short notice and let family and friends in your home country know you are safe."

After organisers took the unprecedented step of cancelling England v France in Yokohama and New Zealand v Italy in Toyota, Ireland's game against Samoa in the southern island of Kyushu is the only match on Saturday.

High waves and gale-force winds are forecast for the area, even though it is out of the path of Hagibis. But a World Rugby spokesman said the game is expected to be played.

"We are confident that the match will go ahead as scheduled," a spokesperson told AFP.

World Rugby also said it would inspect venues for Sunday's four matches immediately after the typhoon has passed before deciding whether they can go ahead, as the crunch Japan-Scotland game in Yokohama hangs in the balance.

The potential cancellation of the Pool A showdown has prompted an ugly row, with Scotland - who will be eliminated if it is called off - threatening legal action.

World Rugby has found itself in the firing line for staging the tournament in Japan, which is prone to typhoons and is also in one of the most seismically active regions on the planet.

But the governing body rejected a British media report that the back-up stadium for England v France was in Tokyo, not far away from the original venue in Yokohama, and that there were no contingency plans for the Japan v Scotland game.

The report was "categorically untrue", a World Rugby spokesperson said.

Even as the fate of Sunday's showdown remained unclear, Japan's players took to a sodden training field in Tokyo - wading through a flooded passageway to get there, widely shared footage showed.

Hagibis, which brought heavy rain and high winds to Tokyo on Saturday, even before it has arrived, has also disrupted the Japanese Grand Prix in Suzuka, where Saturday's qualifying session has been moved to race day on Sunday.

The typhoon is forecast to crash into central or eastern Japan early Saturday evening, packing maximum gusts of 216 kilometres per hour Japan's Meteorological Agency said.

Hagibis is forecast to be the first storm rated 'very strong' to hit the nation's main island of Honshu since 1991, when Japan's category system was introduced.

On Sunday, as well as the Japan-Scotland game, Canada are due to play Namibia in the eastern town of Kamaishi, USA face Tonga in Osaka and Wales are against Uruguay in the country's far southwest, out of the path of the storm.

But most of the attention focuses on the showdown between hosts Japan against Scotland, scheduled to be played in Yokohama near Tokyo at 19:45 (12:45 SA time).

Hagibis will have passed by then but tournament officials will assess the safety of the stadium and transport infrastructure before deciding whether the game can go ahead.

There is much riding on the fixture for both teams, with Japan hoping to reach their first World Cup quarter-final and Scotland desperate to avoid being knocked out.