The officials told Kyodo News the company shipped 5,280 tons of crushed stone from the exclusion zone around Fukushima No.1 power plant to 19 contractors after a March 11, 2011, earthquake-tsunami and subsequent nuclear crisis.
Much of the stone was distributed to a contractor who provided materials for the foundation of the newly built condominium complex in Nihonmatsu, which is within 50 miles of the reactors at Fukushima.
Radiation levels inside the first floor of the complex were found to be at 0.9 to 1.24 microsieverts per hour. The second and third floors had levels of 0.1 to 0.3 and readings outside were 0.7 to 1.
The Environmental Protection Agency in the United States says the average yearly level of radiation in a person living near a nuclear power plant is about 0.0001 to 0.01 microsieverts.
The city of Nihonmatsu conducted radiation tests on the property in September after a young girl living on the first floor recorded an exposure of 1.62 microsieverts over three months.
The Ministry of Economy, Trade and Industry has not imposed restrictions on the crushed stone used in concrete but officials of the quarry firm said all shipments are being investigated for radiation levels.