U.S. employers are having trouble finding workers with the needed skills in science, technology, engineering and math, a top Federal Reserve official said on Monday.

"We are seeing a mismatch of skills in the workforce and the jobs that are being created," Philadelphia Fed President Charles Plosser said of the so-called STEM-trained workers who are in high demand.

"Sadly, we are not doing an adequate job of preparing our workforce for these jobs," he said in remarks prepared for delivery to a conference on reinventing older communities, hosted by his branch of the U.S. central bank.

Plosser did not comment directly on monetary policy or the economic outlook.

He repeated, however, that the labor force participation rate can drop, as it has, for demographic reasons such as the mass retirement of the baby boomer generation.