The breast milk of four Japanese mothers has been found to contain small quantities of radioactive iodine.
This development has led to pressure being brought on the government to initiate a full investigation into the impact of the nuclear disaster on mothers and babies following the discovery.
The radiation contamination came to light after breast milk samples were taken from nine women living northeast or east of Tokyo.
Four of these women were found to be contaminated, with the highest reading of 36.3 becquerels of radioactive iodine per kg detected in the milk of the mother of an eight-month-old baby in Kashiwa, Chiba prefecture, reports media.
There are no current legal safety levels for radioactive substances in breast milk as set by the Nuclear Safety Commission of Japan.