Wearable camera maker GoPro Inc (GPRO.O) reported a much steeper-than-expected fall in quarterly revenue and its forecast for the key-holiday quarter also missed analysts' estimates, hurt by production issues for its newest products.

GoPro, whose shares tumbled 20 per cent after the bell on Thursday, has now reported falling sales for four quarters, in part due to dwindling demand for its body-mounted point-of-view cameras favored by surfers, skydivers and other action junkies.

After a delay, GoPro launched a new camera model, the Hero5, as well as its first consumer drone, the Karma, in mid-September - products that analysts view as instrumental in turning around the company's fortunes.

However, GoPro launched fewer Hero 5 Black cameras and Karma drones than it planned due to production issues that are also expected to inhibit the company's ability to meet demand in this quarter, Chief Executive Nick Woodman said on a conference call.

GoPro said it was now at full production and ramping up distribution of Hero 5, including on Amazon.com Inc. The company had said in mid-October that it had temporarily stopped selling the new camera on Amazon in the United States while it negotiated prices.

The company's revenue declined nearly 40 per cent to US$240.6 million in the latest third quarter, much steeper than the roughly 20 per cent decline analysts on average were expecting, according to Thomson Reuters I/B/E/S.

It forecast current-quarter revenue of US$600 million to US$650 million, below analysts average estimate of US$666.14 million.

The company reported a net loss of US$104.1 million for the quarter compared with a profit of US$18.8 million a year earlier. Excluding items, it lost 60 cents per share, much bigger than analysts' estimates of 35 cents.

GoPro shipped 1.02 million products in the quarter, less than the 1.11 million analysts were expecting, according to research firm FactSet StreetAccount.

Shares of Ambarella Inc, whose video processing chips are used in GoPro cameras, fell 3 per cent in extended trading.

GoPro's shares had closed down 7 per cent in regular trading on Thursday, with investors spooked by fellow consumer gadget maker Fitbit Inc's dismal revenue forecast, also due to production issues.

Including those losses, GoPro's stock is down about 33 per cent this year.