The nation needs a fresh, double-dose of stimulus to counter mounting signs of economic weakness, according to one of the key members of Prime Minister Shinzo Abe's brains-trust of pro-reflation advisers.

The government should assemble a ¥10 trillion fiscal package, and the central bank should add the same amount to its already unprecedented easing program, ruling Liberal Democratic Party lawmaker Kozo Yamamoto said Wednesday.

Speaking in a BS11 television interview, Yamamoto said the fiscal package should include increased benefits for families with children. As well as boosting its purchases of Japanese government bonds, he said the Bank of Japan should buy more exchange-traded funds and other riskier assets.