TOKYO (AFP) - Nine Chinese crew members were missing after two cargo chips collided at the mouth of Tokyo Bay early Tuesday, Japan's coastguard said.

The Panamanian-flagged Beagle III, a 12,630-tonne container vessel, sank after colliding with the South Korean-registered Pagasus Prime in the Uraga waterway.

The accident happened at about 3:10 am (2 am Singapore time).

"Twenty crew members, all Chinese, were on board the Beagle, of whom 11 have been rescued," a coastguard official said.

Patrol ships and a helicopter were continuing to search for the missing crew members about five hours after the accident, the official said.

The crew on the 7,406-tonne Pegasus Prime were unhurt.

The sea was not believed to be rough at the time of the collision, according to the coastguard.