New York, NY (BBN)- The United Nations atomic watchdog agency on Saturday reported that Japan’s nuclear safety body has informed it of an explosion at one of the reactors at the Fukushima Daiichi nuclear power plant, which was affected by yesterday’s massive earthquake, and that an assessment is under way.

The International Atomic Energy Agency (IAEA) said Japanese authorities have extended the evacuation zone around the Fukushima Daiichi nuclear plant to a 20-kilometre radius from the previous 10 kilometers, according to information provided to IAEA by Japan’s Nuclear and Industrial Safety Agency (NISA.)

At the nearby Fukushima Daini plant, the evacuation zone has been extended to a 10-kilometre radius from the previous three kilometers.

Japanese authorities also reported that they are making preparations to distribute iodine tablets to residents in the area of both the plants. Iodine can be used to help protect the body from radioactive exposure.

The IAEA has reiterated its offer of technical assistance to Japan, should the Government request it. The agency said it will continue to liaise with the Japanese authorities, and is in full response mode to monitor the situation closely.

The earthquake, which struck at 2:46 pm local time on Friday, measured 8.9 on the Richter scale. Its epicenter was undersea, about 400 kilometers northeast of the Japanese capital, Tokyo.

The subsequent tsunami inundated towns, villages and farmland along the coast.

Media reports indicate that at least 1,000 people were killed, with the death toll expected to rise significantly. Hundreds more people are missing.

BBN/SSR/AD-12Mar11-11:53 pm (BST)