Japanese Prime Minister Naoto Kan, left, helps to exhume human remains at a mass grave site Tuesday on Iwo Jima island where officials discovered the remains of Japanese soldiers who died during WWII.

IOTO, Japan — In a rare visit to Iwo Jima, Japan’s prime minister offered prayers today at two recently discovered mass graves and vowed to find the more than 12,000 fallen soldiers whose bodies have yet to be recovered from the remote island where some of World War II’s fiercest fighting took place.

Kneeling in a deep pit with dozens of remains spread out before him, Naoto Kan clasped his hands in prayer and then helped searchers exhume a badly decayed set of bones swathed in a faded green body bag. Workers said it was one of more than 20 found today alone.

“We will examine every grain of sand,” Kan said. “It is hard to imagine from the beauty of the island today what happened here 65 years ago.”

Kan said he had wanted to visit the island since the discovery in August of the mass graves.

Now known in Japan as Ioto — that was what the island was called by residents before the war — Iwo Jima was the site of one of the most fateful and iconic battles in the Pacific and helped turn the tide against the Japanese.

For many Americans, an Associated Press photo of U.S. Marines and a Navy corpsman raising the flag atop Mount Suribachi has become one of the most lasting symbols of the war, and of American sacrifice and bravery. More medals of honor — 27, including nearly a third of all given to Marines during World War II — were awarded for valor on Iwo Jima than any other single campaign.

In Japan, however, Iwo Jima is seen by most as just one of many bloody defeats.

It has been generally ignored since the war, has been left largely untouched and is now uninhabited except for a few hundred troops at a small Japanese military outpost. Kan is only the second prime minister to visit the island. Junichiro Koizumi was the first, five years ago.

But Kan’s government, inspired in part by the success in Japan of the 2006 Clint Eastwood movie “Letters from Iwo Jima” and concerned that time is running out, has made a strong effort to bring closure on Iwo Jima by stepping up the civilian-run mission to recover all of the Japanese dead.