The government says it has not detected unusual radioactive materials in rainwater from three cities after North Korea's claimed nuclear test early this week.

The Science and Technology Ministry said Friday that radiation tests showed no abnormal traces of radiation in rain that fell on the northern cities of Gangneung and Chuncheon and the southwestern port city of Gunsan.

The ministry said that it will continue testing to determine effects of the North’s test.

An official at the Korea Institute of Nuclear Safety said that no radioactive impact on the South Korean environment has been seen at this stage.

The official said, however, that the latest tests do not confirm the North actually conducted a test, citing northeasterly winds toward the Sea of Okhotsk above the test site at the time of the alleged nuclear test.