The Ports of Tokyo, Yokohama and Kawasaki -- known collectively as "the Ports of Keihin" -- account for about 40 percent of Japan's foreign trade containers.
The Ministry of Land, Infrastructure, Transport and Tourism is now drawing up guidelines for radiation checks but has yet to set a specific start date, ministry officials said.
In accordance with the guidelines, the three port authorities will measure the radiation levels of ships and containers and issue certificates to prove they are safe, the officials said.
"Any shipping firms, both domestic and foreign, can have the radiation levels of their ships and containers measured if they want," Kinya Ichimura, the ministry's security and emergency management official, told The Journal of Commerce on Monday.
Ichimura also said, "We will start with the Ports of Keihin as they have suffered seriously from harmful rumors. After testing the waters for a while, we will consider whether to expand the coverage of radioactivity measurement to other Japanese ports."
The Fukushima No.1 nuclear power plant, about 140 miles northeast of Tokyo, was ravaged by the devastating earthquake and tsunami that hit the northeastern part of the country on March 11 and has been leaking radiation.
According to the ministry, a total of 27 foreign container ships cancelled visits to the Ports of Keihin between March 11 and April 3. "But we don't know whether all of these cancellations are due to the nuclear accident," a ministry official in charge of the matter told The Journal of Commerce.
Last month, Chinese authorities also turned away the container ship MOL Presencefrom the port of Xiamen, claiming that they had detected high levels of radiation. They allowed it to berth at Honk Kong on Friday after a return to Japan and further testing.
The Japanese Shipowners' Association hailed the ministry's decision. "We highly evaluate it. We want to see the radiation levels of ships and containers actually measured as soon as possible," a JSA spokesman said.
The JSA spokesman said he expects the issuance of official safety certificates will dispel concerns about ships and containers leaving the Ports of Keihin.
Koji Miyahara, chairman of NYK Line, also chairs JSA.