An official in charge of the recovery process of a nuclear waste plant in the U.S. state of New Mexico, which has been shuttered for months due to a radiation leak, said Thursday that it could be up to three years before full operations resume at the underground facility, U.S. media reported.

Jim Blankenhorn, recovery manager of the Waste Isolation Pilot Plant located near Carlsbad in southeastern New Mexico, made the announcement when answering questions from the public during a weekly meeting in Carlsbad, local media KOB said.

Blankenhorn said the timeline continues to be a moving target, but full operations are expected to resume no earlier than 18 months from now.

The underground dump was closed on Feb. 14 when sensors detected unusually high levels of radioactive particles in the air. Crew have made several trips into the dump recently, but the cause of the leak remains unclear.

Inspectors suspect several sealed drums containing nuclear waste from Los Alamos National Laboratory, a leading nuclear weapons manufacturer of the country, might be the source of radiation leak. They are investigating the possibility that there may have been a chemical reaction inside the drums.

The Waste Isolation Pilot Plant stores "transuranic waste" leftover from nuclear weapons research and testing from the nation's past defense activities, according to the Energy Department's website. The waste includes clothing, tools, rags and other debris contaminated with radioactive elements, largely plutonium.