Prime Minister Junichiro Koizumi has effectively admitted that he was only nominally employed at a Yokohama-based real estate company in the early 1970s -- even though he was registered as a member of a public pension system designed to serve full-time corporate employees.

Opposition lawmakers claim that Koizumi may have been illegally registered as a regular worker at Sanpuku Fudosan (Sanpuku Real Estate) from 1970 to 1974.

According to a law related to the "kosei-nenkin" pension program, an employer should be punished if it registers workers whose actual working conditions are not recognized as those of "regular employment."