NEW YORK (CNNMoney) -- American consumers saw prices rise on everything from rent to food to gas last month, as inflation pressures around the world creep higher.

The U.S. Consumer Price Index, a key measure of inflation, increased 1.5% over the past 12 months ending in December, up from 1.1% in November, the Bureau of Labor Statistics said.

On a monthly basis, CPI rose 0.5% in December, from 0.1% growth the previous month -- the largest monthly move since June 2009. Economists surveyed by Briefing.com had expected a 0.4% rise in December.

Most of that increase was due to gasoline prices, which surged 8.5% in December alone, as commodities rallied.

While the increase is a sign that the economy is picking up steam, higher prices can eat into the purchasing power of Americans at a time when unemployment is still high and wages are barely growing.

"It is disconcerting that inflation is starting to accelerate, and you have to wonder, with gas prices moving above $3 a gallon, whether the rate of inflation will continue to escalate," said Bernard Baumohl, chief global economist with The Economic Outlook Group.

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