WASHINGTON (AP) — U.S. wholesale prices rose sharply last month, a sign that stubbornly high inflation may persist after three elevated readings in consumer prices to start the year.

The Labor Department said Tuesday that its producer price index — which tracks price changes before they reach consumers — climbed 0.5% from March to April, after it dipped 0.1% the previous month.

Measured year over year, producer prices rose by 2.2% in April, up from 1.8% in March and the biggest increase in a year.