The state of Japan's public finances is "extremely severe," Finance Minister Taro Aso said on Thursday, vowing to do whatever is needed to boost revenues and cut expenditures to restore the country's fiscal health.

Aso, who is also deputy prime minister, said Tokyo will stick to its goal of turning the primary balance into a surplus by fiscal 2020. The government will map out concrete plans by this summer to achieve the key fiscal rehabilitation target, he said.

"To ensure the credibility of Japan's fiscal policy, we will absolutely implement a consumption tax hike to 10 percent in April 2017," he said in a speech to the Diet, referring to the second stage of the consumption tax hike. The 8 percent sales tax was 5 percent before the first hike last April.