In the latest sign of the seriousness of the Asian crisis, the United States intervened in currency markets Wednesday, selling dollars in an effort to bolster the sagging Japanese yen.

It marked the first time the Clinton administration has ever sold dollars in an effort to support another currency and underscored administration concerns about the deepening economic troubles of the world's second-largest economy.The administration confirmed the dollar sales in a terse, one-sentence statement. "The New York Federal Reserve Bank is operating in the exchange markets on behalf of U.S. monetary authorities," a Treasury Department spokesman said.

The dollar sales sent the U.S. currency plunging in relationship to the Japanese yen, pushing it down almost immediately by more than four yen. Late Tuesday, $1 was buying 143.33 yen, but that dropped after the sales began to 138.15 yen.

The administration action came after heightened worries that the Asian financial crisis, which began a year ago in Thailand, was entering a second, much more dangerous phase that could trigger a worldwide crisis.

Japan announced Friday that its economy was in recession, raising concerns that unless a way could be found to jump-start the Japanese economy, it would pull its troubled neighbors deeper into their own economic slumps.

The Dow Jones industrial average was up 212.49 at 8,877.78 in heavy trading late Wednesday morning, building on Tuesday's 37-point gain and more than wiping out Monday's losses. The Dow plunged 207 points Monday on fear's that Japan's recession would delay the recovery of other Asian economies and hurt U.S. profits.

Treasury Secretary Robert Rubin and other top administration policymakers had been in continual meetings in an effort to decide how the United States should respond to the crisis.

Last week, Rubin had seemed to indicate the United States was not contemplating intervention to sell dollars and buy yen, arguing that such a policy would have only short-lived benefits until Japan did more to solve its own economic problems.

But even as he insisted that intervention should be used only in appropriate circumstances, Rubin expressed new fears about Japan's economic troubles and potential dangerous spillover effects.

"The Japanese economy still fails to show signs of recovery, and Japan's economic difficulties and weak currency are having substantial adverse impact on the East Asian countries," he said.

President Clinton and Japanese Prime Minister Ryutaro Hashimoto conferred by telephone Tuesday night, presidential spokesman Mike McCurry told reporters, saying, "The president of the United States obviously believes this is in an important moment for Japan to deal with the challenges it faces."

In his statement, Hashimoto said Japan realized the revival of its economy was "urgently needed." He pledged, "We will make every effort to restore the banking system to health, to achieve domestic demand-led growth and to open and deregulate its markets, which is of vital importance to Japan, to the recovery of Asian countries affected by financial market turbulence and to the entire world economy."

Meanwhile, China's finance minister issued a pointed warning Tuesday that the Asian crisis could destabilize China's currency. China has so far refused to devalue the yuan, which is also called the renminbi, even after a tide of devaluations swept through Asia last fall. But there were new signs Tuesday that the persistent weakness in the Japanese yen was sorely testing Bei-jing's resolve.

The finance minister, Xiang Huaicheng, said in an article Tuesday in The People's Daily, the Communist Party newspaper, that China's struggle to meet its economic growth target could "increase pressure on the stability of the renminbi." Later in the day, China called on Japan to show the "courage and wisdom" to halt the yen's slide.

The U.S. administration has been pressing Japan for more than a year to take more forceful actions to get its economy moving again.

Hashimoto announced in April details of a $123 billion stimulus package of tax cuts and spending increases.