Far from tightening its fiscal belt, Japan should expand the world's largest debt pile to rekindle economic growth, said former Finance Ministry official Eisuke Sakakibara.

Prime Minister Yoshihiko Noda's push to double the consumption tax to lessen the government's reliance on Japanese government bonds could further damage an economy already struggling amid a slowdown in exports, Sakakibara, known as "Mr. Yen" and now a professor at Aoyama Gakuin University in Tokyo, said in a recent interview.

"We should be selling large amounts of JGBs to fund an economic stimulus," he said. "We could also consider a cut to the corporate tax rate as a stimulus step. The big problem for the Noda administration is there's no one in an important office who understands the economy."