Several German shipping lines suspended calls at eastern Japanese ports, including Tokyo, because of fears crews could be exposed to radiation from the damaged Fukushima nuclear power plant.
Hapag-Lloyd, Germany's biggest ocean container carrier, has stopped calls at Tokyo and Yokohama and is re-routing cargo to Kobe.
Claus-Peter Offen, a leading shipowner with scores of container vessels on charter to leading ocean carriers, is also avoiding Japan's two largest container ports.
Ocean carrier Hamburg-Sud halted calls at Tokyo and Yokohama last week but is now deciding calls on a case by case basis related to weather conditions.
Tokyo and Yokohama handled 7.5 million 20-foot equivalent units in 2010, 38 percent of total Japanese box traffic, according to Alphaliner, the Paris-based analyst.
Most other leading ocean container carriers, including Maersk Line, are operating normal schedules to Japanese ports.
The Journal of Commerce Online