TOKYO (AP) _ The dollar surged against the yen Monday after Japan failed to promise additional steps to boost its economy at the G-7 meeting of top world finance officials. Tokyo stock prices fell.

The dollar bought 128.80 yen at mid-afternoon, up 2.00 yen from late Friday in Tokyo and its late New York rate of 128.00 yen on Friday.

Investors had hoped Japan would promise more government spending to kick start its moribund economy, now in the eighth year of a stubborn slump.

Japan was under pressure to make such a promise at Saturday's meeting in London of finance ministers and central bankers of the G-7, the world's seven largest industrial economies.

The yen had rallied early last week after Japan's parliament approved the use of $230 billion to shore up its ailing banking industry. But that won't be enough to turn the entire economy around, analysts said.

``The weaker yen suggests that investors are concerned about the Japanese economy,'' said Mamoru Otani, a general manager at Daiwa Securities Co.

Uncertainty about how Japan will respond to the G-7 calls for it to boost its domestic economy also dragged down Tokyo stock prices, dealers said.

The benchmark No. 225-issue Nikkei Stock Average dropped 146.75 points, or 0.88 percent, to close at 16,609.49. On Friday, the Nikkei rose 139.76 points, or 0.84 percent.

The Tokyo Stock Price Index of all issues listed on the first section listed on the first section fell 6.11 points, or 0.48 percent, to close at 1,254.58. The TOPIX closed up 2.36 points, or 0.19 percent, on Friday.

Meanwhile, the yield on the benchmark No. 182 10-year Japanese government bond fell to 1.595 percent from Friday's finish of 1.645 percent, driving its price up to 109.48 yen from 109.11 yen.