A government-backed nuclear research agency has apologised for comparing radioactive material on its website to an "angry wife" in a quarrel with her husband, news reports said Tuesday.

The Japan Atomic Energy Agency has already dropped the link from its homepage after the comparison triggered an outpouring of criticism, Kyodo News and other media reported.

On the page, the agency tried to explain the difference between radioactive material, radioactivity and radiation by comparing them to a wife and her behaviour in a marital squabble.

With an illustration, the page noted: "Wife's screaming to her husband can be compared to radiation, her agitated state to radioactivity, and the wife herself to radioactive material."

"We would like to apologise for creating unpleasant feelings," an agency official said, according to the evening edition of the Yomiuri Shimbun.

Japanese people have been nervous about nuclear energy since last year's earthquake and tsunami crippled the Fukushima Daiichi nuclear plant resulting in meltdown and massive radioactive leakage.