U.S. stock index futures point to a lower opening Tuesday, as weak global economic conditions and debt burden in the euro zone continue to drag down the investor sentiment.

Futures on the Dow Jones Industrial Average were down 0.28 percent, futures on the Standard & Poor's 500 index were down 0.40 percent and futures on the Nasdaq 100 index were down 0.25 percent.

Investors are likely to focus on the EU finance ministers' meeting in Brussels Tuesday. On Monday, the ministers decided to give Spain time until 2014 to reach the budget deficit reduction target.

Investors have concerns over some specific measures announced to shore up the euro zone economy, including how soon the proposal for direct bank recapitalization will be implemented and whether bailout funds will be used to purchase bonds in the secondary market.

Investor sentiment is also likely to be affected by the report that China's trade surplus widened in June amid a slower-than-expected growth in imports. According to customs data released Tuesday, China's trade surplus expanded to $31.73 billion in June up 42.9 percent compared to the same month last year.

On Monday, the U.S. markets fell as investors continued to have worries about the second quarter earnings releases over the coming days. There is an increasing concern among market players that the economic slowdown in the euro zone will affect the earnings. The Dow fell 0.28 percent, the S&P was down 0.16 percent and the Nasdaq Composite Index declined 0.19 percent.

Major European indices marginally rose, but investors continued to be concerned about the weakening of the euro zone economic condition. London's FTSE 100 was up 11.82 points, Germany's DAX 30 Index rose 4.64 points and France's CAC 40 advanced 8.30 points.

Asian markets fell Tuesday following global cues. Market players were concerned that the weakening of the domestic demand is hurting the economic growth of China, the world's second largest economy.