Japan raised the incident level at the disaster-hit nuclear power plant Fukushima Daiichi from 4 to 5 on a 1-7 scale on Friday, the International Atomic Energy Agency (IAEA). Experts are considering burying the plant into sand and concrete. It is estimated that over 10,000 people lost their lives.

The UN International Atomic Energy Agency (IAEA) said that situation in earthquake-hit Fukushima Daiichi power plant is worrying but stable.

The current situation at units 1, 2 and 3 of the plant appears to be relatively stable, Graham Andrew, scientific and technical advisor to the head of the IAEA said.

He said officials were still concerned about pools holding spent fuel at reactor units 3 and 4. "Reliable, validated information is still lacking on water levels and temperatures at the spent fuel ponds," he said.

Electricity could be restored on Saturday morning at the reactor 4 at the damaged Fukushima nuclear complex in northeastern Japan, the plant's operator Tokyo Electric Power Co said on Friday.

The Japanese Nuclear Safety Agency said earlier that power could be restored to the reactors 1 and 2 on Saturday morning, Reuters reported.

Japanese engineers, meanwhile, are still trying to cool down the overheated reactors with water, while the Tokyo Electric Power company admitted for the first time that perhaps the only way to prevent radiation release is to bury the whole complex into sand and concrete, which is a method used in the Chernobyl nuclear disaster in 1986.

The problems at the nuclear complex occurred after the 9.0-magnitude earthquake hit northeastern and eastern Japan on March 11, when, due to power cuts, reactor cooling systems failed and started to melt.

Out of Fukushima’s six reactors, four suffered fires, explosions, damages of the structures surrounding reactor cores, as well as partial meltdowns or temperature increases in the pools containing spent nuclear fuel.

The IAEA announced that the incident level in the nuclear complex area was raised on Friday from 4 to 5 on a 1-7 scale.

According to the International Nuclear and Radiological Event Scale (INES), level five indicates an accident with wider consequences, whereas level four is assigned to accidents with local consequences.

The IAEA announced that it will start measuring radiation levels in Tokyo as early as Friday, its Chief Yukiya Amano, visiting the city on Friday, said.

He said that he hopes it would contribute to reassuring the Japanese public, since the international agency will work parallelly with Japan, agencies reported.

The French Nuclear Safety Authority said the disaster at Fukushima reached level six on the INES, ranking the crisis second in gravity to Chernobyl.

Raising the crisis level to five put Fukushima at the same rank as the 1979 accident at Three Mile Island in the USA, when a partial reactor meltdown occured, that led to "very small" release of radioactivity. The accident caused no casualties.

Japanese officials said that they are still hoping that the experts will manage to repair power cable leading to at least two out of six reactors, which would be enough to activate the pumps necessary for cooling down the overheated fuel rods inside reactors.

It is assumed that some 10,000 people died in a devastating earthquake that struck Japan on March 11, causing a tsunami and leading to a nuclear crisis.

The Japanese authorities on Friday confirmed that there are 6,539 dead and 10,354 missing people so far.

More than 410,000 people in 12 prefectures have been evacuated and are staying at shelters, while hundreds of people are waiting for help in remote and isolated areas, without access to food, Reuters reported.

Some 320,000 homes on the north of the country are without power and heating in in near-freezing weather, the Tohuku Electric Power Company said.

At least 87,772 were destroyed in the quake, National Police Agency of Japan stated.

The US Citigroup company estimates that Japan’s economy and infrastructure will suffer 5-10 trillion yen damage, whereas the British Barclays Capital company thinks it will reach 15 trillion yen (USD 183.7 billion). Goldman Sachs expects total economic losses of some 16 trillion yen.