The US economy is growing at its fastest pace in 11 years, in the strongest sign yet that growth has decisively shifted into higher gear.

The US Commerce Department said on Tuesday that the economy grew by an annual rate of 5 percent in the third quarter of this year - between July and September, largely buoyed by consumer spending and investment in business.

The report suggested that unlike other areas of the world where growth was slowing or activity shrinking, the strength of the US economy appeared to have been sustained.

"Our economy is firing on most cylinders, whereas the global economy is essentially in dire need of a spark," Ryan Sweet, a senior economist at Moody's Analytics told the Reuters news agency.

The Commerce Department cited stronger consumer and business spending than previously estimated for the fastest rate of growth since the third quarter of 2003.

Growth in business investment was raised by 1.8 percent to a rate of 8.9 percent, the report added.

Coupled with a hearty 4.6 percent advance in the prior three months, the economy has now experienced the two strongest back-to-back quarters of growth since 2003.

The economy has been benefiting from sinking energy prices, which have helped keep overall inflation ultra-low.

Petrol prices have fallen for 88 straight days, the longest consecutive decline on record.

Cheaper petrol has acted like a tax cut to free up money for Americans to spend on other items, including cars, clothes and appliances.