Having enjoyed a 1.2 percent gain on Thursday, the Euro STOXX 50 index of top European blue-chips dropped 0.3 percent to 2478.57 points when trading resumed. It is course to end the week roughly 1.4 percent lower.

"With concerns over the state of the global economy coming to the fore this week, along with negative sentiment surrounding a Chinese slowdown, and earnings season and the fiscal cliff garnering negative attention in the U.S., visibility for equity markets in the short term remains clouded to say the least," said Daniel Victory at Capital Spreads in London.

A central bank stimulus-inspired rally that pushed global equities up around 15 percent from the lows of early June has stalled this week.

London's FTSE 100 .FTSE, Frankfurt's DAX .DAX and the CAC in Paris .FCHI were all in negative territory at 3.15 a.m. EDT.

Following a flat finish on Wall Street, MSCI's broadest index of Asia Pacific shares outside Japan .MIAPJ0000PUS rose 0.3 percent, but Japan's Nikkei .N225 fell 0.2 percent to its lowest close in more than two months. .T

With many markets stuck in ranges as investors wait to see whether Spain requests a bailout, the euro tracked up to $1.2962. German Bund futures were 21 ticks higher at 141.36 at 3.15 a.m. EDT while Spanish and Italian bond yields were little changed.

Commodities - with the exception of oil - were also mostly set to end the week in the red as investors fretted about the slowdown in China, which is due to release its latest trade data at the weekend.

Gold was trading at $1,769.84 an ounce, on course for a 0.6-percent weekly loss, its sharpest one-week drop in two months.

Tensions between Turkey and Syria continued to support oil, with Brent crude holding above $115 a barrel, set for its biggest weekly gain in two months, while U.S. crude firmed above $92.

"Crude is responding positively to the U.S. economic data and ongoing tensions in the Middle East are adding to supply concerns," said Tim Waterer, a senior trader at CMC Global Markets in Sydney.

Investors were also cautious ahead of a busy day of data which includes what are expected to be upbeat European industrial production numbers later.

With the third quarter U.S. reporting season under way eyes are also on how J.P. Morgan (JPM.N) fares when it posts its results later on Friday in the United States.

(Reporting by Marc Jones; Editing by Giles Elgood)

• A Permanent Economic Emergency