Updated

President Bush, in a phone call Wednesday to Chinese President Hu Jintao, voiced concern about China's crackdown on Tibet and addressed an embarrassing arms shipment flap that has strained U.S.-China relations.

Bush told Hu a U.S. shipment of nuclear missile fuses to Taiwan was a mistake, U.S. National Security Adviser Stephen Hadley said.

"It came up very briefly," 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 U.S.-China ties. It has also triggered a broad investigation into the security of Pentagon weapons.

China on Wednesday strongly protested the mistaken delivery.

In a statement posted on the Foreign Ministry's Web site, 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 matter the details of the situation and eliminate the negative effects and disastrous consequences created by this incident," Qin said.

Bush also told told Hu he was concerned about the crackdown in Tibet, joining a growing chorus of international protests about Beijing's tough tactics.

The White House said that in a telephone call, Bush encouraged Hu to engage in "substantive dialogue" with representatives of the Dalai Lama, the spiritual leader of Tibet. The president also called on China to allow access for journalists and diplomats in Tibet.

China's crackdown in Tibet is in response to the most sustained uprising against Chinese rule in almost two decades — a challenge that has put China's human rights record in the international spotlight, embarrassing and frustrating a Communist leadership that had hoped for a smooth run-up to the Olympic Games.

The White House has said that Bush would not boycott the Beijing Olympics because of the crackdown, arguing that the games are an event that are supposed to be about the athletes, not politics.

French President Nicolas Sarkozy has suggested he might boycott the opening ceremony of the Olympics. Sarkozy, visiting the Houses of Parliament in London on Wednesday, said France and Britain should struggle together for human rights and religious and cultural identity. Sarkozy called for dialogue between China's government and the Dalai Lama.

China on Wednesday showed some signs of relenting, allowing the first group of foreign journalists to visit Lhasha, the regional capital, since the violence began. The reporters were taken to Potala Square, below the Potala Palace, the traditional seat of Tibetan rulers, which reopened Wednesday for the first time since March 14. Then reporters were taken a few blocks away where many shops had been burned out during the rioting.

An account of the talks by Xinhua, the official Chinese news agency, said Hu told Bush that protests in Tibet were by no means "peaceful demonstrations" or activities of "non-violence."

According to the account, Hu said that "no responsible government would sit by and watch when faced with this kind of violent crime, which gravely violated human rights, seriously disrupted social order, and seriously endangered the safety of public life and property."

Bush's conversation with Hu also covered Taiwan, North Korea and Mynanmar.

Bush said the election in Taiwan of Ma Ying-jeou, who has promised to defuse tensions and expand trade with China, would provide "a fresh opportunity for both sides to reach out and engage one another in peacefully resolving their differences."

Xinhua said Hu voiced appreciation to Bush of the oft-stated U.S. position of a one-China policy that opposes Taiwan independence or a referendum on Taiwan's U.N. membership.

Bush and Hu pledged to work together with other partners to press North Korea to make a complete and accurate declaration of all of its nuclear weapons programs and to complete a promised disarmament, the White House said.

Earlier Wednesday, the foreign ministers of the United States and South Korea said Wednesday that patience is running out over North Korea's failure to hand over a promised declaration of nuclear weapon efforts. Pyongyang was to provide a list that was due at the end of last year. The late declaration has bogged down six-nation disarmament talks.

On Myanmar, Bush expressed his concern that the ruling junta of the Southeast Asian nation intends to hold a referendum that was drafted without input from democratic or ethnic minority groups.

"He discussed with President Hu the need for the Burmese leadership to make changes to the referendum process to make it free, fair, and credible to the Burmese people and the international community," the White House said.