Trading generally was light with many markets, including Wall Street, closed for Christmas.
In Europe, France's CAC-40 fell 0.4 percent to 3,893.98 while Britain's FTSE 100 was down less than 0.3 percent at 5,981.29, a day after it broke through the 6,000 mark for the first time since the summer of 2008.
Both markets are only open for half the day while Germany's DAX is closed until Monday.
As a result, trading is proving sluggish though a downgrade of Portugal's credit rating from Fitch Ratings has weighed on sentiment. The downgrade was announced after markets closed on Thursday.
Fitch said it was reducing its rating on the country's debt by one notch to A+ from AA- and warned that further downgrades may be in the offing by maintaining its negative outlook. The agency said it was getting increasingly worried over the country's ability to raise money in the markets to finance its hefty borrowings.
Portugal is widely-considered to be the eurozone country most at risk of needing financial help from its partners in the European Union and the International Monetary Fund
- Greece and Ireland have already suffered the ignominy of being bailed out.
Concerns over Europe's debt crisis have not stopped Europe's stocks rising strongly this year and enjoying their best December for ten years. That's not been the case for the euro, which has been dogged all year by worries that the crisis would spread.
The impact of the downgrade has been muted, given lackluster trading conditions, though the debt crisis will likely be a major influence once again when the bulk of traders in Europe return to their desks in the new year.
"Growth prospects for the eurozone are mediocre, and the attention will remain on any new developments in the sovereign crisis," said Herve Goulletquer, an analyst at Credit Agricole.
By mid morning London time, the euro was flat at $1.3118, while the dollar was unchanged at 83 yen.
Earlier in Asia, the Shanghai Composite index declined 0.7 percent to 2,835.16 and the Shenzhen Composite Index for China's smaller, second market fell 1.8 percent to 1,292.02. Hong Kong's Hang Seng Index closed 0.3 percent lower at 22,833.90