Several tons of waste from former state uranium mine Uramex remains abandoned in an open-air site known as El Puerto, at the border of Mexico's northern Tamaulipas and Nuevo León states, newspaper Crónica reported.
Although unprocessed uranium is not hazardous, it is not known if the abandoned material has been processed or if it shows any signs of radioactivity, the report said.
Potential risks to the environment and public health have not been assessed either.
The mine operated for some years in the 1980s until controlling company Uramex was dismantled due to continuous strikes and scandals in the trade union Sutin, which groups the country's nuclear industry workers.
The mine was located in Cuenca Burgos, which is home to one of the world's most important uranium reserves.
Uramex only managed to extract a few kilograms of the mineral to use as fuel for the Laguna Verde electricity producing facility in Veracruz state.
The waste abandoned at El Puerto is the remnant of the extraction process.
The material is stored in boxes bearing the logo of local mining company Exploraciones y Minas, which is currently active in Nuevo León capital Monterrey.
Company representatives were not readily available for comment to BNamericas.