The US economy grew 2.8 percent in the third quarter, a pace slower than first thought, according to the revised estimate released by the Commerce Department on Tuesday.

The government's new reading on gross domestic product was 0.7 percentage points lower than the 3.5 percent growth rate for the July-September period estimated on October 29.

The increase was also weaker than economists' expectation of 2.9 percent, indicating the rebound was not as energetic as expected.

In the third quarter, US consumers didn't spend as much and commercial construction was weaker. Businesses also trimmed more of their stockpiles. Those were factors that led to the downgrade revision.

The growth of real GDP -- the output of goods and services produced by labor and property located in the United States -- in the third quarter was mainly propelled by the government's economic stimulus package.

Despite downgrading, the 2.8 percent growth still marked the first increase after four consecutive quarters of contraction.

In the first two quarters of 2009, the US real GDP decreased 6.4 percent and 0.7 percent, respectively. In the third and fourth quarters of 2008, the economy contracted 2.7 percent and 5.4 percent.

The new report showed that consumer spending, which accounts for about 70 percent of national economic activity, grew at a pace of 2.9 percent last quarter. That was down from the 3.4 percent growth rate first estimated, but still marked the best showing since early 2007.

Businesses cut back their spending on commercial construction at 15.1 percent annualized pace. That was deeper than the 9 percent annualized cutback first estimated.

Companies also trimmed stockpiles of goods by US$133.4 billion in the third quarter, slightly more than initially estimated.