WASHINGTON — President Bush, addressing an embarrassing flap that has strained American–Chinese relations, told President Hu of China yesterday that the shipment of nuclear missile fuses to Taiwan was a mistake.

The president’s national security adviser, Stephen Hadley, said the matter came up when Mr. Bush called Mr. Hu.

“It came up very briefly,” Mr. Hadley told reporters. “Basically, the president indicated that a mistake had been made. There was very little discussion about it.”

The U.S. military’s mistaken delivery to Taiwan of electrical fuses for an intercontinental ballistic missile has raised concerns over America-China ties. It has also triggered a broad investigation into the security of Pentagon weapons.

China yesterday strongly protested the mistaken delivery.

In a statement posted on the Foreign Ministry’s Web site, a spokesman, Qin Gang, said China sent a protest to Washington expressing “strong displeasure.”

“We … demand the U.S. side thoroughly investigate this matter,” and report to China in a timely manner the details of the situation and “eliminate the negative effects and disastrous consequences created by this incident,” Mr. Qin said. Mr. Bush’s conversation with Mr. Hu also covered Tibet, North Korea, and Myanmar.

“It was a serious conversation on really all of these issues,” Mr. Hadley said.

Mr. Bush told Mr. Hu he was concerned about the crackdown in Tibet, joining a growing chorus of international protests about Beijing’s tough tactics. Mr. Bush encouraged Mr. Hu to engage in “substantive dialogue” with representatives of the Dalai Lama, the spiritual leader of Tibet.