Finding the ¥10 trillion or more to pay for the next economic stimulus package will be a "major task" because of the government's growing debt burden, Finance Minister Kaoru Yosano said Tuesday.

"Japan's fiscal condition is severe," Yosano said at a news conference after Prime Minister Taro Aso ordered him Monday to compile the stimulus measures.

The government's ability to revive the economy is constrained by its debt, which is already the biggest among developed nations and is likely to soar to 197 percent of gross domestic product in 2010, according to the Organization for Economic Cooperation and Development. Bond yields rose Monday to their highest level in more than four months amid concern the government will sell more debt to fund the stimulus.

"Concern about additional debt issuance is huge," said Kazuhiko Sano, chief strategist at Nikko Citigroup Ltd. "Unless the extent of the increase in debt supply due to economic packages becomes clear, it'll be hard for bonds to rebound."

The government aims to compile an outline of the plan by Friday. Vice Finance Minister Kazuyuki Sugimoto said Monday funding the measures will be decided after the package is announced.

Some economists say more spending now is necessary because the cost of doing nothing may be greater in the long run.

"It is worth asking what might happen without an additional fiscal stimulus," said Julian Jessop, chief international economist at Capital Economics Ltd. in London. "The damage to the budget deficit from a deeper and more prolonged recession might make the fiscal position even worse."

Spending will focus on the job market, providing credit to companies, energy-efficient technology and welfare, Yosano said Monday.