Japan marks moment earthquake struck six months ago

The commemoration comes amid ongoing pessimism about the recovery effort and anxiety over radiation leaks from the Fukushima Daiichi nuclear power plant.

Across the vast region hit by the disaster, people bowed their heads in silence at 2:46 pm, the moment a magnitude-9 earthquake – the biggest in Japan's recorded history – struck.

The quake set off a tsunami that would leave about 20,000 people dead or missing, and trigger the world's worst nuclear accident for 25 years.

The tsunami damaged or destroyed 80,000 homes and disrupted supply lines to key industries, while the nuclear crisis spread radiation over large areas and forced the evacuation of about 100,000 people living in or near a 20-kilometre exclusion zone around the plant.

The recovery effort is expected to take years to complete at a cost of hundreds of billions of dollars.

So far, only four of the 31 communities worst affected by the disaster have completed draft reconstruction plans.

The day before the new Japanese prime minister Yoshihiko Noda made his first visit to the tsunami disaster zone, promising local leaders he would speed up the reconstruction effort.

Despite progress in re-housing an estimated 400,000 displaced people and clearing millions of tonnes of debris, many survivors say they face a bleak future.

According to a survey by the public broadcaster NHK, 158,000 people lost their jobs in the three hardest-hit prefectures of Iwate, Miyagi and Fukushima.

Half of those surveyed said they had no prospect of finding work or would lose their incomes within a year.

The Red Cross has complained that the Japanese bureaucracy had delayed the provision of assistance to victims.

"The speed and scope of implementing the response during the emergency phase was not as swift and comprehensive as [we] wished, partly due to the structure of disaster management in Japan, partly because of insufficient preparedness," it has warned in a report.

Last month the government warned that dangerously high radiation levels could make areas near the plant unfit for human habitation for years, possibly decades.