TOKYO: Tokyo Electric Power Co, the operator of the Fukushima Daiichi nuclear power plant disabled by the March 11 earthquake and tsunami, confirmed on Tuesday that there had been meltdowns of fuel rods at three of the plant's reactors early in the crisis.

The government and experts said previously that fuel rods at three of Daiichi's six reactors had likely melted early in the crisis, but the utility, also known as Tepco, had only confirmed a meltdown of fuel rods at the No. 1 reactor.

On Tuesday, Tepco officials announced that fuel rods had also melted at the plant's No. 2 and No. 3 reactors.

Explaining the timing of the announcement, a Tepco official told a news conference that the utility had been gradually retrieving data from the plant since early May, and had analysed it before reaching a conclusion.

“In the early stages of the crisis Tepco may have wanted to avoid panic. Now people are used to the situation - nothing is resolved but normal business has resumed in places like Tokyo,” said Koichi Nakano, a political science professor at Sophia University.

Nakano said that by confirming the meltdowns now, Tepco may be hoping the news will have a smaller impact. The word “meltdown” has such a strong connotation that when the situation was more uncertain, more people probably would have fled Tokyo, he said.

Engineers are battling to plug radiation leaks and bring the plant 240 km (150 miles) northeast of Tokyo under control more than two months after the 9.0 magnitude earthquake and deadly tsunami that devastated a swathe of Japan's coastline and tipped the economy into recession.

The disaster has triggered a drop of more than 80 percent in Tepco's share price and forced the company to seek government aid as it faces compensation liabilities that some analysts say could top dollar 100 billion.

Japanese trade minister Banri Kaieda said the government would approve later on Tuesday the formation of a committee that will make sure Tepco follows through with its restructuring plans.

Also on Tuesday, the government appointed Yotaro Hatamura, a university professor of engineering , to head a committee that will investigate the cause and handling of the nuclear disaster.

Tepco officials said damage to the No. 2 reactor fuel rods had begun three days after the quake, with much of the fuel rods eventually melting and collecting at the bottom of the pressure vessel containing them.

Fuel rods in the No. 3 reactor were damaged by the afternoon of March 13, they said.

Tsunami

The officials repeated that the ensuing tsunami had disabled power to the reactors and knocked out their cooling capabilities.

“It could very well be that Tepco is rushing to conclude that the tsunami is to blame to prevent further questions and give more momentum to the nuclear camp. It's not just Tepco, it's the whole nuclear industry, maybe business circles as a whole. It's highly political,” said Sophia University's Nakano.

Others said that from a very early stage the tsunami, not the quake, was the likely cause of the overheating and subsequent damage of the reactors at Daiichi.

“As with the other nuclear reactors, such as Onagawa (in northeastern Japan), those at Daiichi deactivated after the quake. It is our belief that it was the tsunami that knocked out power and took out the systems and pumps that cool the reactors, resulting in their damage and radiation leakage,” said Kazuhiko Kudo, a Kyushu University professor who specialises in nuclear engineering.

Despite the steady flow of information on how the clean-up is proceeding - Tepco and the government's nuclear watchdog hold news conferences twice a day most days of the week - the authorities have faced criticism for what some have said is a lack of timely disclosure.

“I am very sorry that the public is mistrustful of the various disclosures made by the government on the accident,” Prime Minister Naoto Kan said in parliament on Monday.