The situation of Japan`s Fukushima nuclear power plant remains "very serious" but it appears to have become stable, said the International Atomic Energy Agency (IAEA) Thursday, according to Xinhua.

Speaking at the IAEA`s press conference on the issue of the quake-damaged plant, Graham Andrews, a senior aide to IAEA chief Yukiya Amano, said that "there had been no significant worsening since yesterday."

Andrews said, the Fukushima plant`s Unit 1, 2 and 3 at the moment are in stable condition, sea water are being injected into all three units to cool down the overheated fuel rods, because these three units have got no cooling system.

But he admitted that the situation of Unit 4 is currently unknown and expressed his deep concern. But Unit 5 and 6 remain integral and the temperature is declining, he said.

Radiation in locations around 30 kilometers from the scene of the accident rose significantly in the last 24 hours, he said.