All Japanese ports are closed, and discharging operations stopped after the country was hit by its biggest earthquake on record and a 10-metre tsunami, shippers said.

The 8.9 magnitude quake was the fifth most powerful to hit the world in the past century and rocked Japan's northeast coast. A wall of water killed hundreds of people and swept away everything in its path including houses, ships and cars.

"It's a big mess. All discharge operations are suspended in the area," said a Japanese ship broker.

TV footage showed at least one large panamax vessel, which typically carries 80,000 tons of coal, iron ore and grains, grounded in northern Japan due to the tsunami.

"Most or all coal stocks will be washed out at many of the coal-fired power plants. Ports will be closed at least for a short time period until damage assessments can take place," another ship broker said.

Peter Sand, an analyst with ship association BIMCO, said the country's shipping activity was expected to grind to a halt for now due to the scale of the disruptions.

"In the medium to long-term outlook, demand for shipping may be higher because of this natural disaster," he said.

Freight rates for the dry bulk market are likely to rise as Japanese power plants restock coal inventories and steel companies import more iron ore to rebuild damaged output, ship brokers and analysts said.

"The damage will most probably cause a major requirement for building materials including steel and cement, and drive demand for feedstock such as iron ore and coal," said Thomas Zwick, a shipping analyst with broker Lorentzen & Stemoco.

The Red Cross in Geneva said the wall of water was higher than some Pacific islands, and a tsunami warning was issued for almost the entire Pacific basin, although alerts were lifted for some countries including Taiwan, Australia and New Zealand.

Analysts said several nuclear power plants may be shut for days or possibly weeks.

"Tanker shipping may be impacted as refineries are on fire, which could affect product tanker demand," BIMCO's Sand said.

"Moreover, the nuclear power plant shutdown may also affect overall oil imports for power generation. Both imports and exports may be affected by force majeure."

The quake, the most powerful since Japan started keeping records 140 years ago, sparked at least 80 fires in cities and towns along the coast, Kyodo news agency said. A ship carrying 100 people had been swept away by the tsunami, Kyodo said. (Reuters)