Hapag-Lloyd said it plans to resume calls at Nagoya, Japan, but said its vessels will not return to Tokyo or Yokohama immediately.

Eva Gjersvik, senior director group communication, said the company had only one ship in the country at the time of the tsunami, which left shortly thereafter, and has since confined its calls to Kobe.

"We monitor things very closely. As long as Fukushima is not 100 percent clear, we do not want to take any risk for our crew and ship and cargo," she said.

She noted Hapag-Lloyd is a member of the Grand Alliance, and each member makes its own decision as to which ports to call.

Gjersvik said Hapag-Lloyd is also flagging containers that have come within 100 miles of the Fukushima power station and is taking them out of service temporarily until they can be checked to see if they have suffered any contamination.

American Shipper