Workers are manufacturing products in a factory owned by Foxconn Technology Group. [File Photo: sina.com]

Foxconn Technology Group has seen its December revenues slump by a fifth and full-year sales miss expectations.

The results follow concerns regarding slowing shipments of Apple's latest iPhone 6S models, which Foxconn assembles.

Analysts say the results could be an indicator of demand for Apple's products in the first quarter of this year.

Taiwan-based Foxconn reported December revenue of 12 billion US dollars, down just over 20 percent compared with both a year ago and November.

In 2015, its revenue moved up 6 percent, below analysts' expectations for an annual gain of 7 percent.