HONG KONG (AP) — A nuclear power plant in southern China that supplies electricity to Hong Kong suffered a small radiation leak last month that was contained, the government said Tuesday.

A fuel rod at the Guangdong Daya Bay Nuclear Power Station experienced a "very small leakage" that increased radioactivity levels slightly in the nuclear reactor's cooling water on May 23, Hong Kong's Security Bureau said in a statement.

The leak was "completely quarantined and, therefore, had no impact on the public," the bureau said.

A director at Hong Kong's CLP Group, which owns 25 percent of the power plant, said the leak likely occurred in one of the 41,000 fuel rods inside the nuclear reactor. Richard Lancaster said there was no risk of the radiation leaking outside the reactor because it is thickly encased in steel and concrete.

"It was a very, very minor event," Lancaster said.

With Hong Kong just 30 miles (48 kilometers) away, many nervous residents had opposed the construction of the Daya Bay plant, which opened in 1994, with 1 million people signing a petition against it.

Seventy percent of the output at Daya Bay is allocated to this semiautonomous southern Chinese city.

China's Guangdong Nuclear Investment Co. holds the remaining stake in the plant.