Environment Minister Didace Pembe declined to identify the person who was arrested because investigations were ongoing. He said the waste belonged to a Chinese company called Magma-Lubumbashi, but that the company had not requested the waste be dumped in the Likasi River.
The mining minister for Congo's Katanga province announced on a U.N.-backed radio station that 17 tons of "highly radioactive" minerals had been found in the river on Monday. He did not provide further details and could not be reached for comment.
Authorities have issued calls over local radio stations asking people to avoid using the river to drink or bathe, Pembe said.
The Likasi River runs through a town of the same name and is not far from the village of Shinkolobwe, which provided the uranium used by the United States in the atomic bombs it dropped on Japan at the end of World War II.
Although the main mine shaft at Shinkolobwe was filled with concrete and closed in 1960 by Belgian authorities, uranium is still found in the area and thousands of local diggers have continued working in Shinkolobwe despite a presidential decree again ordering it shut several years ago.
Experts from the International Atomic Energy Agency have played down the dangers of the uranium at Shinkolobwe, saying that enriching the relatively small amounts of uranium found in the surrounding soil at the site to weapons-grade material would be a long and extraordinarily sophisticated process.
The Chinese military believe that Beijing and Moscow must resist pressure from Washington together