NEW YORK, May 12 (Xinhua) -- The U.S. consumer price index (CPI) for April increased by 3.8 percent year on year, up from 3.3 percent in March as energy prices hovered at high levels, data released by the U.S. Bureau of Labor Statistics showed on Tuesday.

The acceleration of U.S. headline inflation in April marks the highest level since May 2023, underlining challenges facing policymakers in the United States.

The index for energy increased 3.8 percent month on month in April, accounting for over 40 percent of the monthly all items increase. In particular, gasoline prices surged 28.4 percent year on year. The index for food increased 0.5 percent month over month in April in comparison to zero growth in the previous month.

Notably, signs emerged that inflation started to expand to core inflation with both shelter and apparel prices in April up 0.6 percent from the previous month. Airline fares in April grew 20.7 percent year on year.

The core CPI, which excludes volatile food and energy components to measure underlying inflation, rose 0.4 percent month on month in April. The core CPI in April rose 2.8 percent year on year, up from 2.6 percent in March.

As headline inflation in April surpassed the 3.6-percent growth in national average hourly earnings drew attention and raised concerns.

Heather Long, chief economist at Navy Federal Credit Union, said for the first time in three years, "inflation is eating up all wage gains."

Sticky inflation is expected to continue to weigh on U.S. households, especially the low-income groups.

"American households are going to continue to struggle trying to manage through this, and that's going to be the case for the foreseeable future," said Moody's chief economist Mark Zandi.