dollar from its freefall, but prospects are slim as long as Washington appears happy to let its currency falter, economists said yesterday.

"There are lots of things the United States and Japan could do, but cooperation as a practical problem is very difficult,'' said Masaru Takagi, chief economist at Fuji Research Institute.

"The US says it wants a strong dollar, but has no sense of crisis and no intention of defending its currency,'' he said.

The dollar plunged yesterday to a fresh post-Second World War low of 79.75 yen in early trade in Tokyo, toppling below its previous low of 80.15 yen set less than 10 days ago.

Prime Minister Tomiichi Murayama quickly pledged that Japan would decisively carry out steps promised in an emergency economic package announced last Friday, including a planned extra budget for the fiscal year which started this month.

But beyond vowing to implement the package, senior government officials offered no new, specific policies to counter the yen's rise.

In Washington, US President Bill Clinton reiterated that the United States wants a strong dollar. But he said governments' ability to affect short-term currency moves is limited, and noted that the United States and Japan have strong differences over trade.

The dollar has plummeted more than 20 percent this year. Its slide yesterday was triggered largely by news of a stalemate in US-Japan talks on trade in cars and car parts.

Despite US rhetoric, market participants believe America wants its currency weak to bolster exports, and the yen strong to prise trade concessions out of Tokyo.

The dollar's outlook was already gloomy after Finance Minister Masayoshi Takemura failed to win more than verbal support for a strong dollar from US Secretary Robert Rubin at a weekend meeting in Indonesia.

Nor did Japan's economic steps and a Bank of Japan discount rate cut on Friday, to an historic low of one percent, impress markets or economists.

Some economists said Japan could do more to help stem the yen's rise, which threatens the nation's economic recovery, by following its economic package with more concrete action.

"They have to make the package concrete, including steps to pass the benefit of the yen's rise on to consumers and to clarify the amount of public works spending,'' Takagi said.

"And Japan should compromise in the trade talks...or there will be no resolution and the yen will rise further,'' he said.

But even more critical to halting the dollar's slide is action by the United States.

Economists say the US Federal Reserve should show its determination to defend the dollar by hiking interest rates, but is unlikely to do so when it next meets to review interest rate policy on May 23.

"There are no Japanese policy measures which could affect currencies in the short term,'' said Susumu Kato, chief economist at CS First Boston (Japan).

"If the US doesn't act, there will be no change.'' YEN HEADS UP -- Bloomberg Business News chart shows the steady rise of the yen against the US dollar since late January.