Major U.S. automakers continued to show signs of a recovery from the COVID-19 pandemic on Thursday as better-than-expected demand for new vehicles despite tight inventories at dealers helped boost third-quarter sales.

Despite posting lower quarterly sales, automakers said the recovery has been robust helped by strong demand for high-profit sports utility vehicles and pickup trucks.

However, rising COVID-19 cases in the United States have increased the uncertainty over a speedy economic recovery.

The third quarter is usually when the industry starts building new models, and piling up inventory for the holiday season. That transition is way behind the normal schedule this year.

General Motors Co reported a 10% fall in auto sales for the third quarter but said sales have improved sequentially each month within the quarter. GM does not break down monthly sales numbers.

The No.1 U.S. automaker said it sold 665,192 vehicles in the quarter, compared with 738,638 a year earlier.

GM said despite tight inventory, its heavy-duty pickup trucks sold well - sales of the Chevrolet Silverado HD were up 9% and GMC Sierra HD were up 11% compared with a year earlier.

"While the economy has made a substantial rebound in the third quarter, retail auto sales have been even more resilient," said GM Chief Economist Elaine Buckberg.

"Super low auto loan interest rates have boosted retail auto sales; yet more strength comes from pandemic-induced demand."

The seasonally adjusted sales pace for the September quarter was expected to be 15.9 million vehicles, up about 4 million vehicles from the previous quarter, GM said.

Toyota Motor Corp's U.S. sales fell 11% in the third quarter. The Japanese automaker said it sold 558,449 vehicles in the quarter, compared with 627,194 a year earlier.

Rival Fiat Chrysler Automobiles NV too reported a 10% fall in U.S. sales to 507,351 vehicles in the quarter.