Mounting petrol prices helped drive US consumer inflation higher in November, pushing the annual measure above the Fed Reserve's target, according to a government report today. 

The news comes as the Federal Reserve is poised to raise interest rates later tonight, the third rate hike of the year.

While it gives some ammunition to those officials worried about the dangers of inflation, there are signs in the report that prices pressures have softened. 

The US consumer price index, which tracks costs for household goods and services, gained 0.4% from October, in line with analysts' expectations.

But the 12-month measure rose by 2.2%. That put it above the Fed's 2% target, although the Fed focuses on a different inflation index. 

Most of last month's increase was driven by energy prices which rose 3.9%, as the price of petrol at the pump surged 7.3% compared to October.

But outside the volatile energy prices, there were signs the price pressures were less pronounced.

Excluding food and fuel, the "core" CPI gained only 0.1% in November, while the 12-month core actually slowed to 1.7%, down from October. 

The November result was unlikely to settle the disagreement among Fed officials about whether inflation will finally accelerate after months of weakness. 

The Fed's preferred inflation measure, the Personal Consumption Expenditures price index, remains well below the 2% target and shows few signs it will rise soon. The 12-month core PCE is just 1.4%. 

While the 12-month CPI measure exceeded 2% for the second time since April, some argue it should be allowed to run higher for some time to compensate for its extended weakness.

The Fed had largely written off weak inflation this year as the product of "transitory" factors such as sudden drops in pharmaceutical and mobile telephone service prices.

But Fed chair Janet Yellen has acknowledged that the Fed's understanding of the forces driving inflation is not perfect.