ST. LOUIS — Radioactive material buried near an underground fire at a suburban St. Louis landfill has been found in areas where it was previously not suspected, but there is no increased health risk to residents or workers, Environmental Protection Agency officials said Thursday.

The EPA released the first phase report of an investigation of the West Lake Landfill in Bridgeton where nuclear waste dating to the Manhattan Project was illegally dumped in the 1970s. Adding to the concern is the fact that an underground fire is smoldering at the adjacent Bridgeton landfill.

Brad Vann, remedial project manager for the EPA, said during a teleconference that health risks associated with the site are unchanged.

In December, the EPA ordered installation of an isolation barrier to make sure that the underground fire — the cause of which is unknown — does not reach the nuclear waste.