The military's flagship hospital has acknowledged it mishandled two packages of radioactive material in May, possibly exposing staff and patients to elevated radiation levels.

Spokesman Chuck Dasey said Thursday that Walter Reed Army Medical Center in Washington doesn't dispute the allegations made by the Nuclear Regulatory Commission. The commission said the packages sat beneath a lobby counter for nearly two days after they were delivered.

Dasey says the hospital has since reinforced its nuclear medicine safety program and retrained staff on the proper handling of radioactive material.

The packages contained radioactive material used to treat and diagnose ailments such as cancer and heart disease.

NRC spokesman Neil Sheehan said no harm has been reported from the incident.