LAS VEGAS (AP) — Federal authorities are investigating whether pepper spray has been used illegally against children housed at two of Nevada’s most secure youth facilities, officials said Thursday.

The U.S. Justice Department announced that it opened a probe of the use of “chemical restraint” at Summit View Youth Center outside Las Vegas and the Nevada Youth Training Center near Elko.

“The investigation will examine whether staff at the two facilities use pepper spray in a manner that violates youth’s rights under the Constitution,” the department said in a statement.

It said no conclusions had been reached about unspecified “allegations in this matter.”

Both facilities are run by the state Division of Child and Family Services. Staff are trained in the use of pepper spray under the division's use-of-force policies, which were updated last July, social services chief Karla Delgado said in an email.

According to the policy, pepper spray can be used for justifiable self-defense, to protect a young person from hurting themselves or others, to stop “significant property damage” or an escape, to quell a riot or “substantial disturbance, or “to overcome the physical resistance of a youth for failing to comply with a reasonable directive by staff.”

Force should be limited to what's necessary to get control of a situation and ensure safety, the policy says, and must decrease “proportionally to a level sufficient to maintain control.”

Staff are required to issue warnings and exhaust “all other measures” before using pepper spray, and a review is done every time it's deployed, Delgado said.

A 2006 report to the Legislature by the Institute for Children’s Research and Policy at the University of Nevada, Las Vegas, said the Nevada Youth Training Center housed a daily average of almost 150 children ages 12 to 18 at that time at its 500-acre facility.

The Division of Child and Family Services reports that the center is now funded for 60 young people.

Summit View is a maximum-security facility with 48 beds on a 13-acre campus in North Las Vegas, not far from Nellis Air Force Base.

A 2001 Justice Department investigation found “prevalent” excessive use of force by Nevada Youth Training Center staff, an inadequate grievance system and improper use of seclusion and “time out” discipline, among other shortcomings. The report did not address the use of pepper spray.

“Frequently, incident reports and other NYTC documentation fail to justify why staff used force and why other non-physical interventions were not implemented,” investigators said.

The Justice Department said it was accepting “relevant information” about the new probe by email at Community.NVJuveniles@usdoj.gov.