In a televised debate with Mr Aso on Sunday, he said Japan's relationship with the US would continue to be the "cornerstone" of his foreign policy.

Mr Fukuda said he wanted to continue logistical support for the war in Afghanistan despite growing opposition at home.

He also said he wanted to pursue a more conciliatory approach with Japan's neighbours China and North Korea.

On Saturday, Mr Fukuda announced he would not visit the contentious Yasukuni shrine, which Japan's neighbours see as a symbol of the country's past militarism.

His rival, Mr Aso, called China's growing military spending a threat to Japan and the region.