Japanese Prime Minister Shinzo Abe visited Iwo Jima on Sunday to review efforts to recover the remains of those killed in fierce fighting on the Pacific island during World War II.

Japanese Prime Minister Shinzo Abe visited Iwo Jima on Sunday to review efforts to recover the remains of those killed in fierce fighting on the Pacific island during World War II.

The conservative leader attended a memorial service to remember those who perished in the final months of the war in one of the bloodiest battles between US and Japanese troops.

Some 22,000 Japanese soldiers are thought to have died on the island, which lies some 1,200 kilometers (750 miles) south of Tokyo and is officially known as Iwoto, but the remains of most of them have yet to be recovered.

In 2010, Tokyo launched a three-year project to recover more remains, saying it was a question of national duty to bring them back and lay them to rest.

Nearly seven decades after the war ended in 1945, Japan is still trying, with limited success, to collect remains of its war dead.

Some 2.4 million Japanese soldiers died overseas during the war. Nearly half of them -- 1.13 million -- have no proper resting place, having died in battlefields spread over a vast area between Russia and the South Pacific.