Japan said Thursday, March 31, there were no immediate plans to widen the exclusion zone around its stricken nuclear plant, hours after the UN atomic watchdog agency voiced its concern over the issue.

The UN atomic watchdog said Wednesday radiation in a village outside the evacuation zone around the plant was above safe levels, urging that Japan reassess the situation.

In its first such call, the International Atomic Energy Agency added its voice to that of Greenpeace in warning over radioactivity in Iitate village, where the government has already told residents not to drink tap water, AFP reports.

Japan's top government spokesman, Chief Cabinet Secretary Yukio Edano, confirmed that "the IAEA has informed us that the level of radiation in the soil exceeded one of the IAEA standards."

"And the IAEA has advised us to carefully assess the situation on the basis of this report," he told a regular press conference.

When asked by a reporter whether Japan would now expand the exclusion zone, he said: "I don't think that this is something of a nature which immediately requires such action."

Japan has struggled to contain its nuclear emergency since a 14-metre (45-foot) tsunami hit the Fukushima plant after a huge quake on March 11, with radioactive substances entering the air, sea and foodstuffs from the region.