All Japanese ports have closed, with discharging operations halted, after the country was hit on Friday by an 8.9 magnitude quake and tsunami, shippers said.
The biggest earthquake to hit Japan in 140 years struck the northeast coast, triggering a 10-metre tsunami that swept away everything in its path, including houses, cars and farm buildings on fires.
"It's a big mess. All discharge operations are suspended in the area," said a shipbroker.
TV footage showed at least one large panamax vessel, which typically carries 80,000 tonnes of coal, iron ore and grains, grounded in northern Japan due to the tsunami, a second Tokyo-based shipbroker said.
"Most or all coal stocks will be washed out at many of the coal fired power plants," he said.
"Ports will be closed at least for a short time period until damage assessments can take place."
Shipbrokers expected freight rates to rise in the short-term as Japanese power plants restock their coal inventories and steel companies import more iron ore as part of the rebuilding process.
A tsunami warning has been extended to the whole of the Pacific basin, except for mainland United States and Canada, following the earthquake in Japan, NOAA's National Weather Service said on Friday.
The warning includes Mexico and Central and South American countries on the Pacific, NOAA's Pacific Tsunami Warning Center said.