A Tepco sampling survey at the tsunami-crippled Fukushima nuclear plant has found fish around the plant that contain extremely high levels of radiation.

Professor Shugo Watabe explains it is possible the fish accidentally ate mud that may have contained radioactive materials while feeding on shrimp.

He says the contamination is likely to be limited but it was important to prevent contaminated fish from being sold or consumed.

This is not the first time that fish from around Fukushima have been found with radiation but these are reportedly the highest levels found so far.

Many fish from Fukushima are still prohibited from being sold to consumers.