The Bank of Japan appears to be wavering in its commitment to unprecedented monetary easing, said Kozo Yamamoto, an adviser to Prime Minister Shinzo Abe and an advocate of reflationary policies.

"I'm worried the BOJ's attitude is wavering," Yamamoto said in an interview in Tokyo on Friday. "I wonder if Kuroda is being affected by fukumaden," he said, which translated means "a den of conspirators."

Yamamoto made the remarks after Gov. Haruhiko Kuroda signaled confidence that consumer price gains remain on track for a 2 percent target, even as inflation ground to a halt by the bank's key gauge. The Abe administration is pursuing a strategy of shock therapy to revive the world's third-biggest economy with steps including record purchases of government debt by the central bank.