The erroneous shipment of the fuses, which can be used to trigger warheads on ballistic missiles, was only discovered last week, the Pentagon said on Tuesday.

"We express our serious concern and strong dissatisfaction and demand the US side investigate this incident," foreign ministry spokesman Qin Gang said in a statement.

"We urge the US to cease selling military hardware to Taiwan and end US-Taiwan military ties, or risk harming stability in the Taiwan Strait and the healthy and stable development of China-US ties."

Nose cone assemblies containing the fuses were recovered on Monday from Taiwan where they had been held in storage after being shipped there as helicopter batteries, senior Pentagon officials said.

US Defense Secretary Robert Gates has ordered an investigation into the incident and a comprehensive review of the US inventory of all nuclear-related components as well as of policies and procedures, the officials said.

"We'll do a thorough investigation, and those who are responsible will be held accountable. The secretary is quite forceful on this," said Ryan Henry, principal deputy undersecretary of defense for policy.

It was the second major nuclear security breach uncovered in just over six months, following the mistaken transfer of nuclear armed cruise missiles from one US base to another aboard a B-52 bomber in September.

"Our policy on Taiwan arms sales has not changed. This specific incident was an error in process only and is not indicative of our policies, which remain unchanged," Henry said.

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