US wholesale inflation registered its biggest increase in three decades in November, prompted by higher petrol prices, official figures show.
Wholesale price inflation contrasts with recent consumer inflation
The producer price index, which measure the cost of goods from US factories, farms and refineries, rose 2% last month, well above forecasts.
The US Labour Department figures saw the core index - which exclude volatile food prices and energy - rise 1.3%.
November's increase challenges the notion that inflation is under control.
The US Federal Reserve left interest rates unchanged at 5.25% last week, but continued to voice concerns over inflation.
November's rise comes after wholesale inflation declined by 1.6% in October.
As a result, some analysts say the latest figures do not give cause for concern and simply offset the previous month's fall.
"Over the last year, producer prices, including food and energy, have risen only 0.9%, and consumer price inflation is likely to moderate through the early months of 2007," said Peter Morici, economist at the University of Maryland.
The latest producer price increase is not yet reflected in consumer prices, which were flat in November.
While analysts had predicted a rebound in wholesale prices in November after October's fall, the 2% figure was four times greater than expected.
Energy prices were 6.1% higher last month, with gasoline prices soaring by just under 18%.
In another development, construction of homes and apartments rose by 6.7% last month, but applications to build homes fell for the 10th month in a row, Commerce Department figures showed.