A South Korean nuclear reactor shut down Thursday due to a technical malfunction, the latest in a series of glitches that have raised public safety concerns

The Uljin-1 reactor, 330 km (206 miles) southeast of Seoul, was tripped off by what a spokesman for the Korea Hydro and Nuclear Power Co said appeared to be a faulty gauge.

"There has been no radioactive leak and there is no health hazard involved. It was an automatic shutdown for safety," the spokesman told AFP, adding that an investigation was underway to confirm the precise cause.

It was the second time in less than six months that the same reactor has automatically shut down, and two other reactors at separate plants did the same in October because of unspecified systems malfunctions.

South Korea operates 23 nuclear power reactors which meet more than 35 percent of the country's electricity needs.

Half of the six reactors at one of the country's largest nuclear power complexes, Yeonggwang, were shut down in November, two of them to replace "non-core" parts that had been provided with forged quality and safety warranties.

The shutdowns fuelled safety concerns and raised the spectre of power blackouts during what has turned out to be a particularly severe winter.

There has been a series of official power alerts in the past month -- automatically triggered by reserves running lower than four million kilowatts for more than 20 minutes.

The government has vowed to stick to its nuclear power programme and plans to build an additional 16 reactors by 2030.