The government should decide on a supplementary budget within a month or two, a veteran politician and economic adviser to Prime Minister Keizo Obuchi said Wednesday.

Ichizo Ohara, a member of the ruling Liberal Democratic Party and a former agriculture minister, said that's how long it will take to make sure long-term interest rates won't rise if an extra budget is announced. A rise in long-term rates could cause stocks to crash, which would endanger banks and other publicly held firms.

"I think the time is coming (for the government) to decide on the scale and contents of a supplementary budget, if long-term interest rates do not rise when government bonds worth 3 trillion yen are being issued every month," Ohara told a luncheon at the Foreign Correspondents' Club of Japan in Tokyo.