As H1N1 swine flu continues to spread throughout the country, a controversy has erupted over what import agencies claim is legal online trading of Tamiflu, one of the best-known medicines for treating flu viruses.

Only Tamiflu produced in Japan can be sold here, and getting it requires a prescription.

A number of Web-based import agents are trading the imported version at much higher prices than the ¥309.1 per capsule designated for the domestic version.

The businesses are operating in a legal gray zone. Although the Pharmaceutical Affairs Law says it is illegal to "sell" and "advertise" unapproved drugs, such businesses claim they are only taking "service fees" for importing Tamiflu on behalf of customers who are unfamiliar with import procedures.

Some traders are selling 10 capsules for around ¥7,000 to ¥8,000, Web sites show. Others charge as much as ¥12,000.

An official in the health ministry's compliance and narcotics division said imported Tamiflu is not recommended because of safety concerns.

"It is important to take medicine following proper directions (authorized by the government) and it is dangerous to do otherwise," the official said.

He said the quality of unapproved drugs can be questionable and warned that the drugs can even be fake.

Chugai Pharmaceutical Co. is the only authorized importer of Tamiflu in Japan.

A spokesman for one of the agents, who declined to be named, said there is nothing wrong with foreign-made Tamiflu or with providing a decent agent service to people who want to import the product.