SEOUL - Over 20 bodies were found in South Korea's battery plant fire site, in which 23 workers had been believed to be trapped, Yonhap news agency said Tuesday citing police and the fire authorities.

The fire broke out at a primary battery plant in Hwaseong, around 45 km south of the capital Seoul, at about 10:31 am local time (0131 GMT).

Some 35,000 lithium batteries were estimated to be stored on the second floor of the three-story reinforced concrete factory with a total floor area of 2,300 square meters or so.

The fire authorities mobilized 159 firefighters and 63 pieces of equipment, but they struggled to extinguish the fire because of the difficulty in putting out the flame of lithium batteries.