Japanese troops will on Monday fan out across the areas hardest hit by last month's earthquake and tsunami, searching for bodies on land and sea in a joint, two-day operation with police, coast guard and US military personnel.

Some 25,000 soldiers face the grisly task of picking through rubble and plumbing the waters off the Japanese coast, looking for the 12,000 who remain missing and are presumed killed after the March 11 disaster.

The confirmed death toll stands at about 14,300.

"We will do our utmost to recover bodies for bereaved families," said Defense Ministry spokesman Ippo Maeyama on Sunday.

"It's been very difficult and challenging to find bodies because the areas hit by tsunami are so widespread," he said. "Many bodies also have been swept away by the tsunami."

The operation -- the third and largest of its kind since the quake -- will include 90 helicopters and planes. Boats and divers will also search the waters up to 20 kilometers off the coast.

Previous searches were complicated by the decomposition of some bodies, said Maeyama. Some had already turned to skeletons.

"You have to be very careful in touching the bodies because they quickly disintegrate," he said.

Meanwhile, a team of veterinarians is headed to the area surrounding the stricken Fukushima nuclear power plant to check on and perhaps put down the hundreds of thousands of cows, chickens and pigs that were abandoned when the area was evacuated.

Many are presumed to have already starved to death. Others may be euthanized, pending approval of the owners, said officials.

With files from Associated Press