The metropolitan government said Tuesday it has not detected any radioactive substances in its tap water following North Korea's fourth nuclear bomb test conducted Jan. 6.

The Office of Waterworks under the Seoul municipal government said the tap water for 10 million Seoul citizens has been confirmed safe as a result of its examination of artificial radioactive elements, such as cesium-134.

Conducted from Jan. 6 through Jan. 12, the city government tested Han River water collected at four water intake facilities, as well as the tap water supplied by two Arisu purification facilities under the city government.

Arisu, the old name of the Han River that runs through the capital, is the city's bottled tap water. The Seoul city also said it has not seen any radioactive elements in its monthly examination of the city's tap and bottled water conducted since 2012.

The examination of the Han River water was made at five intake facilities, and the tap water was examined at six Arisu filtering centers, a city official said.

A city official said the city will expand the number of elements subject to examinations to 12, including lead-124 and uranium-238.  

Han Kuk-young, the chief of the waterworks office, said his office will continue to reinforce the inspection of the possible radioactive substances to ease the public's anxiety.  (Yonhap)