U.S. stock index futures point to a lower open on Friday ahead of the publication of the Bureau of Labor Statistics' nonfarm payroll and unemployment reports.

Futures on the Dow Jones Industrial Average were down 0.17 percent, while futures on the Standard & Poor's 500 Index were down 0.13 percent and those on the Nasdaq 100 Index were down 0.11 percent.

“The fate of the markets for the rest of the day is far from certain and we should learn a lot of the psychology of the market by the end of the U.S. session,” Chris Weston, chief market strategist at IG Markets in Melbourne, wrote in a note to Bloomberg.

“Today is non-farm payrolls day foremost, and there is every chance we see another day of heightened volatility, with almost all asset classes likely to move to an ever-changing view on QE,” he said, referring to the Federal Reserve’s bond-buying program, also known as quantitative easing.

The government's monthly nonfarm payroll report will be released at 8:30 a.m. EDT on Friday and will provide clues to the sustainability of the country's economic recovery and the future of the Fed's bond-buying program.

Economists polled by Reuters predict the nonfarm payroll report, which measures the change in the number of people employed during the previous month, excluding the farming industry, to show a gain of 170,000 jobs in May, up from a gain of 165,000 jobs in April, while the unemployment rate is expected to remain unchanged at 7.5 percent.

“An improving labor market is the crucial factor for Fed policymakers in determining the appropriate amount of monetary accommodation they should target in the asset purchase plan in coming months. The strength of May payroll gains will be a major element in the formulation of market expectations on the timing of any tapering moves by the FOMC,” said a note from Credit Agricole.

The much-awaited official employment data follows weaker-than-expected reports on private-sector hiring and weekly jobless claims, all of which showed weakness in the labor market. Data released earlier this week showed that factory activity in the world’s largest economy unexpectedly contracted in May and the private sector created a fewer-than-expected 135,000 jobs.

European markets were trading mixed as investors opted for caution ahead of the employment report from the U.S. London’s FTSE 100 was down 0.09 percent, Germany's DAX-30 fell 0.01 percent, while France's CAC-40 gained 0.22 percent.

Earlier, Asian stocks declined to fresh 2013 lows, with most indices falling for a third straight session. The yen’s overnight rally against the dollar weighed on exporters' shares hurting the Nikkei, which ended down 0.21 percent, up from day's lows. Hong Kong's Hang Seng fell 1.21 percent and South Korea's KOSPI slumped 1.80 percent, while China's Shanghai Composite slipped 1.22 percent. India's BSE Sensex was trading up 0.25 percent in late afternoon trade.