A Japanese professor has unearthed documents that show the Vatican helped with the postwar repatriation of Japanese held in camps in Siberia and elsewhere.

Matsumoto Saho, a professor of international liberal arts at Nihon University, says her findings are a new discovery of the Vatican's role in the repatriation efforts.

An estimated 6.6 million Japanese, including former soldiers of the now-defunct Imperial Japanese military and civilians, remained abroad after the end of World War Two. Many of those detained died, while some survivors had to wait for more than 10 years before returning home.

Matsumoto found about 40 diplomatic documents among materials made public by the Vatican, the headquarters of the Roman Catholic Church. The documents cover the Vatican's repatriation efforts from 1946 to 1948.

Some detail the Vatican's moves to help repatriate Japanese nationals interned by the former Soviet Union. More than 570,000 are known to have been held in camps in Siberia and other Soviet regions.

An official telegram that a Vatican ambassador to Japan sent to the Vatican's secretary of state in January 1947 shows the ambassador asked the United States to accelerate talks with the former Soviet Union to expedite repatriation.

Other papers show a group of Japanese families of internees sent a letter to the Vatican secretary of state in August 1948. The group asked for cooperation to bring home their loved ones by the year-end, and a reply letter vowed efforts to realize this at an early date.

Another official telegram sent by the Vatican ambassador to the Vatican secretary of state in August 1947 said a request had been made to the Dutch government for better treatment of Japanese nationals held in the Dutch East Indies, now Indonesia.

In December 1947, another group of Japanese families sent a letter to the Vatican ambassador saying that repatriation from Southeast Asia had almost been completed and expressed gratitude for the Vatican's assistance.

Matsumoto says Japanese likely sought help from the Vatican, a neutral state, well-known for its Christian humanitarianism.

Matsumoto also says the Vatican extended help not just for humanitarian reasons, but possibly with the political intention to prevent the spread of Communism.

She says there were risks that Japanese detainees, particularly those in Siberia, could have been brainwashed by the Soviets.