Japan was warned more than two years ago by the international nuclear watchdog that its nuclear power plants were not capable of withstanding powerful earthquakes, leaked diplomatic cables reveal.
An official from the International Atomic Energy Agency (IAEA) said in December 2008 that safety rules were out of date and strong earthquakes would pose a "serious problem" for nuclear power stations.
The Japanese government pledged to upgrade safety at all of its nuclear plants, but will now face inevitable questions over whether it did enough. While it responded to the warnings by building an emergency response centre at the Fukushima plant, it was only designed to withstand magnitude 7.0 tremors.
Friday's devastating earthquake was a magnitude 9.0 shock.
According to a report in the Telegraph, the news is likely to put further pressure on Japan's Prime Minister, Naoto Kan, who has been criticised for "dithering" over the country's response to the ongoing crisis at the Fukushima nuclear power plant.
Panic started to spread throughout Japan yesterday following the news that a third explosion at the plant might have damaged the protective casing around the reactor core, increasing the threat of radioactive leaks.
The government was considering using helicopters to spray water over the Fukushima site to limit the spread of radioactive particles as part of its increasingly desperate attempts to keep the situation under control.
Warnings about the safety of nuclear power plants in Japan, one of the most seismologically active countries in the world, were raised during a meeting of the G8's Nuclear Safety and Security Group in Tokyo in 2008.
A US embassy cable obtained by the WikiLeaks website and seen by The Daily Telegraph quoted an unnamed expert who expressed concern that guidance on how to protect nuclear power stations from earthquakes had only been updated three times in the past 35 years.
The document states: "He [the IAEA official] explained that safety guides for seismic safety have only been revised three times in the last 35 years and that the IAEA is now re-examining them.
"Also, the presenter noted 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."