BEIJING -- China strongly protested to the U.S. on Wednesday over the mistaken delivery of fuses for long-range missiles to Taiwan, the latest incident involving arms sales to the island to roil relations between Beijing and Washington.

"We ... demand the U.S. side thoroughly investigate this matter, and report to China in a timely matter the details of the situation and eliminate the negative effects and disastrous consequences created by this incident," Qin said.

He reiterated China's long-standing demand that the United States halt all weapons sales and military-to-military contacts with Taiwan, the self-governing island that Beijing has claimed as its own since the sides split amid civil war in 1949.

Ending those practices would help Washington "avoid damaging peace and stability in the Taiwan Strait and the healthy development of China-U.S. relations," Qin said.

The U.S. Embassy in Beijing said it had no immediate comment on China's statement.

U.S. officials have moved quickly to mollify Beijing over the mix-up in which the Pentagon mistakenly sent four cone-shaped fuses for intercontinental ballistic missiles to Taiwan in August 2006 instead of helicopter batteries ordered by the island's military.

The fuses, for use in Minuteman strategic missiles, are linked to the triggering mechanisms of nuclear warheads but contain no nuclear materials themselves. The fuses were returned after the foul-up was realized late last week, and an investigation headed by Navy Adm. Kirkland H. Donald was ordered.

It was the second nuclear-related mistake announced by the U.S. military in recent months. Last August, an Air Force B-52 bomber was wrongly armed with six nuclear-tipped cruise missiles at a base in North Dakota and then flown to Louisiana. Its crew wasn't aware nuclear arms were aboard.

Ryan Henry, the No. 2 policy official in Defense Secretary Robert Gates's office, called the mistaken shipment of the fuses to Taiwan intolerable and said President Bush as well as Chinese leaders were informed of the matter once it was discovered.

Henry said if the incident violated any treaty or agreement, it was unintentional.

"We are being totally transparent. We have corrected the situation," he said. "The United States stands up to its treaty obligations and we're dealing with this in the most straightforward manner we can."

"The U.S. recently informed us that the parts had been mistakenly sent to Taiwan, and they asked us to dispose of the parts by ourselves," said Wu Wei-rong, director-general of Taiwan's armaments bureau, on Wednesday.

"The U.S. then realized the parts were sensitive, controlled items which Taiwan could not deal with, and soon the parts were returned," the senior Taiwan defense official said.

The error raised major concerns because of its link to nuclear weaponry and China's sensitivity about the United States supplying arms to Taiwan.

Beijing routinely complains about the weapon sales. While its anger is usually intense but short-lived after a deal is announced, the issue has occasionally led to serious tremors in its up-and-down relationship with Washington.

Most recently, U.S. approval of the sale of missiles and anti-submarine warfare planes to Taiwan was believed to have triggered Beijing's rejection of Hong Kong port calls by the USS Kitty Hawk aircraft carrier group last fall. China hinted its response was also prompted by the U.S. Congress honoring the Dalai Lama, the exiled spiritual leader of restive Tibet.

Taiwan is the most sensitive issue in U.S.-China relations.

Despite the lack of a U.S. defense pact, or even diplomatic ties with Taiwan since Washington opened formal relations with Beijing in 1979, America is the island's biggest arms supplier, selling it about $10 billion worth of arms between 1999 and 2006.

U.S. law also requires that the Pentagon ensure Taiwan can defend itself -- a provision interpreted by some as meaning U.S. military forces could help repel any attack on the island.

On the Net:

Defense Department: www.defenselink.mil