SANTA FE, N.M (Reuters) - The Los Alamos nuclear weapons laboratory has ended a state of emergency and was taking small steps on Saturday toward reopening as the threat from a record New Mexico wildfire subsided.

But highlighting the need for continued vigilance, a squirrel sparked a small blaze on lab property on Saturday when it touched a transformer. That fire, which measured about an acre, was quickly extinguished, the lab said in a statement.

Officials have yet to set any reopening date for Los Alamos, but with the risk to the laboratory and adjacent town mostly passed, lab director Charles McMillan said employees were slowly being prepared for reopening the lab.

"We've assessed the risk to the lab to be lower so we've changed the status based on that assessment," McMillan told a news conference.

The Las Conchas Fire consumed an additional 9,000 acres on Friday, and now stands at 113,734 acres, burning primarily toward the north, and further onto the western flank and into the Valles Caldera National Preserve.

A firefighting force of nearly 1,800 people working to douse the flames has managed to carve containment lines around 6 percent of the fire's perimeter on its eastern and southern flanks, keeping the blaze from invading the lab complex.

Now ranked as the largest wild-lands blaze ever in New Mexico, the fire surpasses the previous record set in 2003 by the 94,000-acre Dry Lakes Fire in the Gila National Forest.

By comparison, the largest blaze in Arizona, the Wallow Fire, has blackened well over 500,000 acres since it erupted May 29 of this year. It is still burning.

At one point this week, the New Mexico fire's edge was reported just 2 miles from a collection of about 20,000 metal drums containing plutonium-contaminated clothing and other waste stored on a corner of the 36-square-mile lab property.

Nuclear watchdog groups and some citizens had raised concerns about the fire possibly unleashing residual ground contamination left from decades of experimental explosions and waste disposal in the area.


The first employees to return to the Los Alamos lab, one of the nation's top nuclear arms production facilities, would be checking on the facilities, including air handling systems to be sure there was no clogging from the smoke, and bringing IT systems back on line, McMillan said.

A lab spokesman, Kevin Roark, said select employees would start returning on Saturday and that process would continue throughout the week. About 150 people were in the lab on Saturday, and an additional 100 would be there on Sunday.

McMillan said the status change at the lab would allow resources to be moved away from Los Alamos to focus on other areas, particularly in the north of the state where the fire continues to grow.

Officials have set no time for lifting evacuation orders for the town of Los Alamos, whose 10,000 residents fled earlier this week. Thick smoke lingered over the area.

The blaze has also encroached on an Indian reservation to the north, the Santa Clara Pueblo, burning at least 13,000 acres of tribal land, including a number of sacred sites.

"We, the generation of today, have seen a beautiful canyon and traditional lands that have been our home for centuries destroyed in a matter of days," Santa Clara Pueblo Governor Walter Dasheno said, pleading for emergency federal assistance.

"Our canyon is the source of our Santa Clara Creek that we rely upon for irrigation but, more than that, it was a beautiful place of abundance in wildlife, clean water, culturally-significant trees and medicinal plants," he said.

The leading western edge of the blaze had remained about 6 miles from the nearest populated areas of the pueblo on Friday, fire officials said at the time.

On Saturday, firefighters were conducting burnout operations to protect cultural sites near the reservation, and archeologists were working with fire crews to minimize damage to sensitive areas, fire information officials said.

A lightning strike sparked a fresh fire east of the main wildfire, but it was quickly contained, and wetter conditions helped moderate the bigger blaze, the officials said.

About 150 miles to the south, a separate wildfire caused by lightning blazed in and around the Mescalero Apache Reservation. By Saturday, the Donaldson Complex Fire had burned some 90,000 acres, including several thousand acres on tribal land, but was 30 percent contained, authorities said.

(Editing by Cynthia Johnston and Greg McCune)

Mochila insert follows.