Updated

Los Alamos National Laboratory says it made mistakes in packaging the waste that has been linked to a radiation leak at the government's underground nuclear waste dump in southeastern New Mexico.

In a letter released by state regulators Friday, lab officials say their internal probe of the handling of the toxic waste from decades of nuclear bomb building has uncovered several violations of its Hazardous Waste Facility permit. But lab officials say it's unclear if the violations are to blame for the February leak at the Waste Isolation Pilot Plant in Carlsbad that contaminated 22 workers and shuttered the repository indefinitely.

Teams of scientists and engineers have been trying to determine exactly what caused a barrel from Los Alamos to burst, as well as whether a switch from inorganic to organic cat litter to absorb moisture was a contributing factor. The lab says it failed to follow proper procedures in making the switch and in its testing and packaging of highly acidic waste that contained lead.