A rise in radiation levels at Japan’s stricken Fukushima nuclear plant has forced workers to suspend operations, a government spokesman says.
He was speaking after smoke was seen rising from reactor three. Earlier, a blaze struck reactor four for the second time in two days.
Friday’s 9.0-magnitude earthquake and tsunami, which killed thousands, damaged the plant’s cooling functions.
The site has also been hit by four explosions, triggering radiation leaks.
France has urged its nationals living in Tokyo to leave the country or head to southern Japan because of the risk of radiation.
On Wednesday, Japanese Cabinet Secretary Yukio Edano told a news briefing that workers at the Fukushima Daiichi plant had been withdrawn following the sudden rise in radiation levels.
It is believed that about 50 employees had been working at the plant – 220km (140 miles) north of Tokyo – to try to cool its four reactors and avert a meltdown.
Mr Edano also said that the radiation levels were now falling from 1,000 millisieverts on Wednesday morning to 600-800.
But that was still more than average, Mr Edano said, adding that “workers cannot carry out even minimal work at the plant now. Because of the radiation risk, we are on standby.”
The new fire at reactor four was reported early on Wednesday. Three hours later, Japan’s nuclear safety agency said flames could no longer be seen.
But white smoke was later seen rising from reactor three. Officials are investigating the cause of both incidents and the damage done, with Mr Edano saying the smoke was probably steam from the evaporation of water, which caused the higher radiation.
“A part of the containment vessel is broken and it seems like the vapour is coming out from there. So… [it] appears to be that vapour is coming out from the broken part.”
Twenty-four hours earlier, on Tuesday morning, another fire broke out in the spent fuel storage pond at reactor four.
The reactor had been shut down before the quake for maintenance, but its spent fuel rods are still stored on the site.
Kyodo news agency says the storage pool may be boiling and further radiation leaks are feared.
The Tokyo Electric Power Co (Tepco), which operates the Fukushima plant, said it may pour water and fire retardant from helicopters to stop fuel rods from being exposed to the air and releasing even more radioactivity.
The crisis at the plant – which has six nuclear reactors – began when the earthquake struck. Explosions rocked the buildings housing reactors one and three on Saturday and Monday.
On Tuesday morning, a third blast hit the building of reactor two, while a fourth damaged the building of reactor four.
Officials say the explosions at the first three reactors, and possibly the fourth as well, were caused by a buildup of hydrogen.
Mr Edano has said that cooling seawater is being pumped into reactors one and three – which are returning to normal – and into reactor two, which remained unstable.
People living within 20-30km (12-19 miles) of the site have been told to either leave the area or stay indoors.
More than 3,300 people have been confirmed dead and thousands are missing after Friday’s quake and tsunami.
In the north-eastern town of Otsuchi, the fate of half of the population – around about 8,000 people – remains unknown.
More than 500,000 people have been made homeless by the quake and tsunami.
Many are enduring snow and freezing temperatures, as supplies begin to reach the worst affected areas.
The government has deployed 100,000 troops to lead the aid effort and the army is also using helicopters to bring in basic supplies.
Strong aftershocks continue to rock the country. A 6.0 magnitude tremor struck in the Pacific just off Chiba prefecture, east of Tokyo, on Wednesday.
On the Tokyo stock exchange, the Nikkei index recovered some ground, after plummeting 17% over the previous two days.
The UK Foreign Office has updated its travel advice to warn against all non-essential travel to Tokyo and north-eastern Japan. British nationals and friends and relatives of those in Japan can contact the Foreign Office on +44(0) 20 7008 0000.