The electric-car maker Tesla's losses widened in the second quarter as it continued to invest in factories to accommodate the introduction of its first mass-market vehicle.

Tesla said it lost $US401.4 million ($503.7 million) in the quarter that ended June 30, compared with a loss of $US293.2 million in the same period in 2016.

The company also reported overall growth in its operations, which includes its automotive business and its solar-panel division.

Tesla said its total revenues for the quarter were $US2.79 billion, more than double the $US1.27 billion it recorded in the comparable period last year.