Strong US and China car sales and a drop in costs for the faulty ignitions recall helped General Motors double profits in the third quarter, the Detroit automaker reported Tuesday.

Sales in the two key markets helped offset ongoing slumps in Europe, South America and elsewhere, with unit sales up 3.8 percent from a year ago to 2.42 million cars and trucks in the quarter, helped by a 17.3 percent jump in China.

The company meanwhile warned that its hopes for a return to stability in Europe were at risk to fallout from Britain's vote to pull out of the European Union, including the weak pound.

"Breaking even in Europe this year is going to be very very challenging," said GM chief financial officer Chuck Stevens.

Net profits jumped to a better-than-expected $2.77 billion from $1.36 billion a year ago.

The key difference was a net $1.6 billion decline in costs for the recall of millions of cars for faulty ignition switches and dealing with related litigation for injuries.

Total revenues were up 8.6 percent to $40.33 billion, while costs fell by $2.9 billion to boost operating margins.

Earnings per share, adjusted for special items and dilution, were $1.72, far better than the $1.42 expected.

Bolstering its full-year outlook, GM said it expects 2016 adjusted earnings to come in at the high end of the $5.50-$6.00 a share range it set at the end of the second quarter. Earnings in 2015 were $5.02 a share.

"Our record third quarter, led by strong performance in the US and China, reflects our determination to deliver on our commitments. We will continue executing our plan to deliver earnings that enhance shareholder returns," GM chief executive Mary Barra said in a statement.