After two days' delay, the reactor was installed at the power plant of the state-run Taiwan Power Co. (Taipower) in northern coastal town of Kungliao, a Taipower spokesman said.

Taipower Chairman Lin Ching-chi says this would be a "milestone development" in the project, which is almost 60 percent completed but behind schedule.

The Japanese-built 1,000-tonne reactor has been on site since June 2002, the first of two planned.

However, Wu Wen-tung, head of a Kungliao group opposing the nuclear power plant, issued a stern warning against the project, which he said "could become Taiwan's largest nightmare in the future".

"We've repeatedly called attention to the flaws of the power plant -- the civil engineering construction and the rust of the reactor. But the government has turned a blind eye to our warnings," he said.

The project has been mired in controversy for years and became a campaign point in the 2000 presidential elections which brought Chen Shui-bian of the opposition Democratic Progressive Party (DPP) to power.

In October 2000, the DPP scrapped the partly built 5.6 billion US dollar plant without consulting parliament, as required by Taiwan's constitution, plunging the island into months of political crisis.

The DPP government opposed nuclear power on grounds of safety and difficulty in disposing of the waste, but reinstated the project in February

Because of the delay, Taipower is estimated to need another 1.3 billion US for the project, with the extra spending awaiting parliament's approval.

The first nuclear reactor had been scheduled to begin operation in July 2006 and the second in July 2007, with a total capacity of 2,770 megawatts.

Since Taiwan's first nuclear plant became operational in 1987, nuclear power has generated at least 180,000 drums of low-radiation waste.

Taipower had planned to ship the waste to North Korea but was forced to halt the scheme under pressure from South Korea and international conservationists.

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