Japan is marking the first anniversary of a magnitude-9.0 earthquake and tsunami in the northeastern part of the country, which triggered the world's worst nuclear disaster since the 1986 Chernobyl accident.
More than 19,000 people died or went missing in the March 11 twin natural disasters, which also destroyed more than 370,000 houses.
At 05:46 GMT, the precise moment when the earthquake struck one year ago, a moment of silence was observed across the country.
Speaking at a ceremony in Tokyo, Yoshihiko Noda, Japan prime minister, pledged "to speed up ... the reconstruction of the affected areas " and to strengthen nationwide natural disaster measures. He also thanked the volunteers, both foreign and Japanese, who helped with the reconstruction work.
"Predecessors who led Japan's prosperity said that crisis is sometimes necessary in order to grow. We need to support the people who were affected by the earthquake and reconstruct Japan from this historic disaster. And that is my mission," he said.
Japan's Emperor Akihito also made a rare public address at the same ceremony, paying tribute to those lost and the volunteers who helped in rescue and rehabilitation efforts.
"These kind of activities gave hope and consolation to people who were forced to live very uncomfortable lives," he said.
"And at this opportunity, I would like to extend my gratitude to people who have been working for the affected people. Also I would like to pay my gratitude to those people who are working at the in the [Fukushima nuclear] power plant and overseas rescue teams, and many people have worked very hard to help us."
"The siren sounded across Rikuzentakata, a Buddhist temple bell was also sounded as the minute's silence was observed around this town," Al Jazeera's Harry Fawcett reported from the northeastern coastal town, which was among those worst hit by the earthquake and tsunami.
"The memorial ceremony is still going on, at a specially constructed tent on the grounds of the high school. People are queueing up outside, despite the fact that already nearly 3,000 people are inside there, there are many more queueing up outside with floral tributes to pay to the more than 1,700 dead of Rikuzentakata."
Yuki Takahashi, a local business owner who worked as a volunteer in the days following the disaster, told Al Jazeera the memorial ceremony was "very important for me, and for people of [the city], because we sadly lost many friends and parents, just in one day. So it's very tragic, we shouldn't forget this".
Many roads have been rebuilt and most debris has been cleaned up but 260,000 people still live in temporary housing in the prefectures of Iwate, Miyagi and Fukushima.
Critics say recovery has been painfully slow and the authorities have squeezed most of the disaster victims into tiny prefabricated housing units located far from city centres.
|In-depth coverage one year after triple disaster
The nuclear crisis has forced more than 80,000 residents to leave areas around the Fukushima Daiichi Nuclear Power Station, which went into meltdown after it was struck by the tsunami. A series of fires and blasts led to massive release of radioactive substances into the environment.
The government set up a no-go zone of a 20km radius around the plant in late April.
On Sunday, about 16,000 people gathered near the plant to take part in a anti-nuclear energy demonstration.
The demonstrators, who included citizens, refugees, activists, children and foreigners, gathered at a baseball stadium in Koriyama, about 60km away from the plant, calling for an end to the country's use of nuclear energy and compensation for the victims of the disaster.
"Our town has turned out to be another Chernobyl," Masami Yoshizawa, who ran a cattle farm in Namie, 10 kilometres from the plant, shouted through a loudspeaker.
"We are in despair now, but I will get back my hometown even if it takes me the rest of my life," said Yoshizawa as he stood atop a wagon displaying pictures of his cows lying dead in their shed.
A group of monks in brown and white robes chanted Buddhist sutras as activists carried banners reading: "We never forget the March 11 Great Earthquake. We will never forgive the nuclear accident."
Yukiya Amano, chief of the International Atomic Energy Agency (IAEA), said on Friday that human error had played a significant role in the nuclear disaster at the plant operated by Tokyo Electric Power Company (TEPCO).
"One reason that allowed the unfolding of the accident was the lack of independence of the regulatory body in Japan. The Japanese regulatory body was not robust enough, and the oversight over the operator was weak," he said.
The Nuclear and Industrial Safety Agency is under the Ministry of Economy, Trade and Industry, which has promoted nuclear power generation.
Anti-nuclear protests were to be held on Sunday around the country, including one in Koriyama in Fukushima prefecture, where 15,000 people were expected to gather, organisers said.
Despite the fallout of the disaster, the IAEA insists nuclear power is safer than it was a year ago.
In a statement issued before the first anniversary of the world's worst nuclear crisis since Chernobyl in 1986, Amano said meaningful steps had been taken to strengthen global nuclear safety.
The comments were criticised by environmental groups. Greenpeace, which opposes nuclear energy on safety grounds, said that "no real lessons" appeared to have yet been learnt from Fukushima.
"Industry and politicians around the world quickly [carried out] so called stress tests only to conclude that no single
reactor in the world is unsafe and needs to close," Jan Beranek, head of Greenpeace's nuclear campaign, said.
"No doubt even Fukushima Daiichi would have passed those tests," he said.
The IAEA "even said that the main problem was how to restore public confidence - instead of looking into how to better protect people. This must change, or [the] next nuclear disaster is inevitable".
Images of the stricken plant and the enormous devastation the tsunami wrought across Japan shook public confidence in nuclear power and forced the nuclear industry to launch a campaign to defend its safety record.