South Korea was forced to shut down two nuclear reactors Monday to replace components provided with fake quality certificates, a minister said, warning of "unprecedented" power shortages to follow.

Knowledge Economy Minister Hong Suk-Woo stressed that the "non-core" components posed no safety threat and were unrelated to a string of systems malfunctions at reactors this year that triggered calls for a safety review.

The two affected units at the Yeonggwang nuclear complex in the southwest may have to remain off-line until early January, as engineers replace more than 5,000 fuses, cooling fans and other parts provided by eight suppliers.

"Comprehensive safety check-ups are necessary at these two reactors where the uncertified parts were used extensively," Hong said.

AFP