The U.S. intelligence community has recently concluded that Iran is aggressively seeking to develop a nuclear weapon and that China has provided Iran with equipment capable of making some fissile material for such a weapon, according to Bush administration officials.

Discovery of the Chinese sale to Iran comes amid disclosures of an unexpectedly advanced nuclear weapons program in neighboring Iraq. Some U.S. analysts now suspect that Iran may be seeking to do what Iraq has been blocked from doing and build a nuclear weapon that can be brandished in the Middle East.

As recently as June, U.S. officials said there was no evidence that China was assisting any effort by Iran to make nuclear weapons. Administration officials said their new concern about Iran's intentions was heightened last week when a senior Iranian official expressed interest in building a nuclear arsenal to match that believed held by Israel.

In an interview distributed by the official Iranian news agency, deputy president Ataollah Mohajerani said that "because the enemy has nuclear facilities, the Muslim states too should be equipped with the same capacity."

Mohajerani, who normally is responsible for legal and parliamentary affairs but occasionally speaks for Iranian President Ali Akbar Hashemi Rafsanjani on foreign policy matters, said "Muslims should strive to go ahead" because nuclear weapons can enable countries to achieve a military superiority over potential enemies.

"I am not talking about one Muslim country, but rather the entirety of Muslim states," he said, noting that "we witnessed the destruction of Iraq's nuclear devices" by parties that he said have no business interfering in such matters.

U.S. officials said the remarks may represent a significant statement of Iranian intentions. "Iran is trying to do things on the cutting edge of nuclear technology that they would not find interesting if they did not have weapons in mind," said one official, adding that the Iranian program is still believed to be at an earlier stage of development than was Iraq's program before the start of the Persian Gulf War last January.

While declining to provide details, the official said the U.S. intelligence community had concluded after a review that Iran is seeking "much more {technology} than would be needed" to develop a civilian nuclear power network, which Iranian officials routinely have claimed is their sole objective.

"They have tremendous social needs, and they are a major exporter of oil, yet they are spending all this money on nuclear-related equipment," the official said. "It doesn't make any sense."

In addition to evidence of nuclear cooperation between Iran and China, administration officials cite recent efforts by Iran, so far unsuccessful, to obtain nuclear-related technology from Brazil. A U.S. government analyst, speaking on condition he not be named, said 90 percent of what Iran is seeking from foreign suppliers can be used equally for nuclear weapons and civilian power, providing a ready "cover" for the weapons-related work. Officials said the Iranian shopping list includes nuclear fuel, equipment for handling and processing fissile materials, and nuclear reactors to replace those destroyed in the 1980-88 war with Iraq.

China signed an agreement in June 1990 to provide what it described as a "micro-nuclear reactor" for installation at Esfahan in central Iran. It also has provided training for Iranian nuclear engineers and sent delegations of scientists to Iran, a U.S. government source said.

But the Iranian purchase from China that recently caught U.S. attention involved calutron equipment worth millions of dollars, according to government officials. The equipment is considered capable of producing highly enriched uranium -- a vital component of nuclear weapons -- through a process of electromagnetic isotope separation.

Officials described the equipment as similar to the calutron devices discovered in Iraq last summer during international inspections there. Iraq had been preparing secretly to operate hundreds of the relatively crude devices, leading U.N. experts to estimate that the Baghdad regime could have produced a single nuclear weapon in 12 to 18 months.

The quantity of Chinese-made equipment sold to Iran was not sufficient to produce even a single bomb's-worth of enriched uranium, U.S. officials said. But they said the sale amounts to a significant transfer of technology that Iran could readily duplicate.

"You would not use calutrons for a civilian nuclear power program," said Leonard S. Spector, a nuclear proliferation expert at the Carnegie Endowment for International Peace here. "What's disturbing is that the recipient can take such a device and advance rapidly without extensive foreign assistance" in producing a sufficient quantity of enriched uranium for a single bomb.

Several officials said that China's sale of the calutron equipment appeared at odds with routine assurances by Beijing that it neither encourages nor participates in nuclear proliferation, nor provides assistance to other countries in developing nuclear weapons. They said the sale appeared to grow out of the close Iranian-Chinese ties developed during the mid-1980s, when government-affiliated corporations run by family members of senior Chinese leaders made huge profits by selling to both sides during the Iran-Iraq war.