Former Japanese Ambassador to Lebanon Naoto Amaki, a strong critic of Prime Minister Junichiro Koizumi's foreign policy, will challenge Koizumi in his single-seat constituency in Kanagawa Prefecture in the Sept. 11 general election for the House of Representatives, sources close to the ex-diplomat said Thursday.

Amaki, 58, plans to run as an independent in the Kanagawa No. 11 district, which covers the cities of Yokosuka and Miura.

He was quoted as saying he wants "to question the diplomatic policies of the prime minister, who has been repeating mistakes, such as supporting the war in Iraq and the dispatch of the Self-Defense Forces there."

Days before the U.S. and its allies invaded Iraq in 2003, Amaki, as Japan's ambassador to Lebanon, sent a telegram to Tokyo urging the government not to support the U.S.-led war and later resigned from the Foreign Ministry.