In what appeared to be a veiled warning, one of Prime Minister Shinzo Abe's most influential economic advisers has said he "doesn't have to rush" into the first stage of the sales tax hike unless the economy and the labor market have recovered.

The Abe administration plans to make its final judgment on whether to proceed with the tax hike, which will raise the rate to 8 percent from 5 percent next April, this autumn. Adviser Koichi Hamada's hint, however, could affect Abe's decision.

If the consumption tax is hiked before the economy has recovered, tax revenue will dry up, the 77-year-old professor emeritus of economics at Yale University said Wednesday, hinting that the Japanese economy might shrink after the hike.