Four Americans missing off Okinawa

A YACHT with four US citizens aboard went missing today in waters south of the East China Sea as Typhoon Jangmi pounded the area, the Japanese coast guard said.

The coast guard said it was searching for the yacht after its office on the southern Okinawa island received a radio distress signal overnight.

"We then confirmed it was a US-registered yacht, Jade Princess, with the US coast guard," the Japanese coast guard official said.

Four US citizens are aboard Jade Princess, which was sailing from Malaysia to Okinawa, the official said.

"We received the signal shortly before noon from a location some 83km south-southwest of Iriomote island," he said, referring to a small Japanese island near Taiwan.

The typhoon is the strongest to hit Taiwan this year. It is expected to reach Japan's Okinawa island chain by Wednesday, according to the Japanese Meteorological Agency.

Jangmi, meaning "rose" in Korean, made landfall in Taiwan's north-eastern Ilan county around 5.40pm AEST yesterday, according to local officials.