Kyodo News reports the United States has informally conveyed its concern to Tokyo over Japanese Prime Minister Shinzo Abe's recent remarks concerning Japan's imperial history.

Citing U.S. and Japanese sources, the news agency said a U.S. State Department official conveyed concern through the Japanese Embassy in Washington about adverse effects the Abe administration's moves regarding historical issues may have on relations with its neighbors.

Prime Minister Abe recently reaffirmed his views on Japan's imperial past and defended visits by Japanese Cabinet members and lawmakers to the Yasukuni Shrine to pay homage to Japanese war dead.

The report said Washington's expression of concern appears to be related to Abe's remarks on the definition of "invasion" and the visits to the controversial war shrine.