OMAHA, Neb. (AP) — Federal inspectors said they found an alarming number of defects in the locomotives and railcars Union Pacific was using at the world's largest railyard in western Nebraska this summer, and the railroad was reluctant to fix the problems.

Federal Railroad Administrator Amit Bose wrote a letter to UP's top three executives Friday expressing his concern that the defects represent a "significant risk to rail safety " on the Union Pacific railroad.

Bose said the 19.93% defect rate on rail cars and the 72.69% rate for locomotives that inspectors found in July and August are both twice the national average. But the letter didn't detail what kind of defects inspectors found in the Bailey Yard in North Platte, and there are a myriad of federal rules.

"The compliance of the rolling stock (freight cars and locomotives) on the UP network is poor, and UP was unwilling or unable to take steps to improve the condition of their equipment," Bose said in his letter.

Bose questioned whether the recent layoffs of 94 locomotive craft employees and 44 carmen across the Omaha, Nebraska-based railroad that is one of the nation's largest left UP without enough people to complete the necessary repairs.

Kristen South, a spokeswoman for Union Pacific, said Sunday that the layoffs weren't a problem, and the railroad remains committed to safety.

"Union Pacific will never compromise on the safety of our employees. Safety is always our first priority, and we are reviewing and will address the concerns raised by the FRA," South said.

Railroad safety has been a key concern nationwide this year ever since another railroad, Norfolk Southern, had a train derail and catch fire in eastern Ohio in February. That East Palestine derailment prompted regulators and members of Congress to call for reforms, but few significant changes have been made since then.

South said the railroad has appropriate staffing levels with enough capacity to have "a buffer to allow for the natural ebb and flow nature of our business."

Those layoffs that UP announced late last month came after the FRA wrapped up its inspection, and they represent a tiny fraction of the railroad's workforce that numbers more than 30,000.

Union Pacific's new CEO Jim Vena just took over the top spot at the railroad last month. Union Pacific has a network of 32,400 miles (52,000 kilometers) of track in 23 Western states.