Japan's economic growth beat expectations in the July-September period, helped by stronger exports to expand for a third straight quarter, but weak domestic activity cast doubt on hopes for a sustainable economic recovery.

Government data issued on Monday data underscored a potentially fragile export-reliant economic recovery just as Republican Donald Trump's shock victory in the U.S. presidential election added to uncertainty over the global economic outlook.

The economy expanded by an annualized 2.2 percent in the third quarter, faster than the 0.9 percent increase markets had expected, following a 0.7 percent increase in April-June, Cabinet Office data showed on Monday.

It marked the third straight quarter of expansion.

The preliminary reading for gross domestic product (GDP) translated into a quarterly expansion of 0.5 percent in the third quarter, versus a 0.2 percent gain expected by economists.

Private consumption, which accounts for roughly 60 percent of GDP, rose 0.1 percent, unchanged from the second quarter, a sign the effects of Prime Minister Shinzo Abe's stimulus drive dubbed Abenomics are yet to spread to households due to tame wages.

Capital expenditure, a key component of GDP, was flat, following a 0.1 percent decline in the second quarter, with worries about the global outlook and renewed yen gains weighing on business investment.

External demand - or exports minus imports - added 0.5 percentage point to GDP, due to a bounce in exports from the prior quarter, and falling imports caused by yen gains, oil price declines and weak domestic demand.

It marked the biggest contribution since April-June 2014.