General Motors reported lower fourth-quarter car sales Friday as a lengthy US worker strike continued to pinch auto inventories.

The biggest US automaker delivered 735,909 vehicles during the quarter ending December 31, down 6.3 per cent from the year-ago period.

At year's end, the company had inventories of 616,023, down 18.4 per cent.

Although the figures demonstrated the continued drag from a 40-day strike that ended in late October, executives touted strong sales of larger sport utility vehicles and pickup trucks.

Sales of "full-size" pickup trucks and SUVs topped one million during the year.

"Our fourth-quarter stocks were leaner than we wanted, but as we get ready to launch our all-new full-size SUVs, we look forward to another solid year in 2020," said GM vice president for US sales Kurt McNeil.

"We've focused our resources on what our customers want -- crossovers and trucks -- and that has paid off."

GM had previously signaled that the strike would weigh on fourth-quarter results, saying in October that the stoppage would cut about $3 billion from 2019 earnings.