Many of the companies on Saturday avoided Tokyo Bay, which is home to two major ports of Tokyo and Yokohama.
Chinese officials had detected radioactive contamination in their cargo ship having sailed at least 80 miles farther from the Fukushima Daiichi nuclear power plant that was damaged by the March 11 earthquake and tsunami.
Although some cargo ships enter ports south of Tokyo, many others have totally cancelled any shipment to Japanese ports until further notice.
Ports in China and Hong Kong say they will scan vessels and cargo from Japan for radiation.
In Long Beach, California, Coast Guard officials boarded a ship from Japan and scanned it with hand held devices to assuage fears of longshoremen who wanted the scanning done before the ship got too close.
“We put safety ahead of everything else,” said Eva Gjersvik, senior director for communications at Hapag-Lloyd, a German shipping firm.
The nuclear crisis seems to be worsening as new safety worries complicate efforts to control the situation at the power plant. Radioactive iodine 1,250 times above the legal limit has been detected in the waters off the quake-hit site.
The Japanese government has criticized the plant’s operator, saying it must be more transparent and provide information more promptly.