By Sylvia Westall and Fredrik Dahl
VIENNA (Reuters) - The U.N. atomic energy chief said he planned to fly to Japan on Thursday to seek first-hand information of what he called a very serious situation at a stricken nuclear power plant in his home country.
Director General Yukiya Amano of the International Atomic Energy Agency (IAEA) said he intended to request an extraordinary meeting of its 35-nation governing board as soon as possible after he returned to Vienna.
Amano's announcements of his trip and the board session made clear his growing concern over the crisis in Japan.
It also suggested frustration at the Vienna-based agency, which is tasked with fostering the safe use of nuclear energy, about the lack of speedy and detailed information from Japan.
"It is different to receive facts by email from Tokyo to sitting down with them and exchanging views," Amano told a news conference. "We always need to improve the flow of information."
He said he hoped to meet high-level Japanese officials but it was not decided whether he would go to the site of the severely damaged Fukushima plant during his one-day trip.
But he said it was not the time to say whether developments at the site had spiraled out of control, as suggested by a European Union energy official in remarks that sent global share markets lower.
"The operators are doing the maximum to restore the safety of the reactor," Amano said.
He said the IAEA had continuously been trying to help improve the safety of nuclear power plants against earthquakes.
But he declined to comment on a report, in Britain's the Daily Telegraph newspaper, that U.S. cables obtained by WikiLeaks said Japan had been warned more than two years ago by an IAEA official over the possible impact of earthquakes on nuclear power plants.
The unnamed official was quoted in the document as saying that "recent earthquakes in some cases have exceeded the design basis for some nuclear plants, and that this is a serious problem that is now driving seismic safety work."
In Japan early on Wednesday another fire broke out at the earthquake-damaged facility, which has sent low levels of radiation wafting into Tokyo in the past 24 hours, triggering fear in the capital and international alarm.
"It is a very serious situation," Amano said.
Damage to the cores of units 1, 2 and 3 at the Fukushima Daiichi nuclear reactor has been confirmed, although there has been no serious change there since Tuesday, he said.
He suggested the water was at a level that left up to two meters of the cores holding the fuel rods exposed, even though the pressure inside indicated the reactor vessels remained "largely intact."
Japanese media have criticized the government's handling of the disaster and plant operator Tokyo Electric Power Co. for its failure to provide enough information on the incident.
The IAEA, which has as a mandate to share information with member states when there is a nuclear emergency, has also been criticized in the media and in comments posted on its Facebook page for providing scant and out-of-date information.
The IAEA says it can provide only the information it receives and verifies.
(Editing by Elizabeth Piper)