The U.S. stock index futures point to a lower open Monday as investors continue to worry about the weakening economy with the rising debt burden faced by the euro zone and the declining global growth rate.

The futures on the Dow Jones Industrial Average were down 0.38 percent, the futures on the Standard & Poor's 500 Index were down 0.41 percent and those on the Nasdaq 100 Index were down 0.34 percent.

The continuing debt crisis in Europe and the tentative U.S. recovery have hurt the market sentiment. In spite of the fact that the major central banks around the world have announced monetary easing measures to bolster the global economic growth, market participants worry that these steps will not be sufficient to lift the weak economies.

On Friday, the U.S. markets were mixed as investors maintained a cautious mode. The Dow Jones Industrial Average rose 0.26 percent, the S&P 500 Index was down 0.03 percent and the Nasdaq Composite Index declined 0.42 percent.

European markets fell Monday as investor sentiment turned negative with the revival of the concerns over the debt crisis affecting the euro zone following the continuing financial instability in Greece and the delay in Spain asking for a bailout officially.

Talks between Greece and the Troika, which consists of the European Commission, the European Central Bank and the International Monetary Fund, will continue in Athens on the austerity measures to be implemented to receive the bailout fund.

Meanwhile, hopes that Spain will soon ask for a bailout officially has faded with Prime Minister Mariyano Rajoy denying the need for a financial rescue. But the investors feel that it would be unwise if the government wait too longer.

London's FTSE 100 was down 35.66 points, Germany's DAX 30 index fell 62.03 points and France's CAC 40 declined 35.04 points.

Asian markets fell Monday as investors remained watchful due to the concerns over the revival of the global economic growth in spite of the stimulus measures announced last month by the policy maker in the U.S. and Europe. Stock markets in Japan were closed Monday for holiday.

Meanwhile, China's services activity growth rose in September after a fall in August, according to the HSBC Purchasing Managers' Index (PMI) released Monday. The services PMI rose to 54.3 in September, up from 52 in August, indicating the improvement in business activity. The index continues to remain in the area of expansion since the reading is above 50. Also the rise in the reading would decrease fears of the likelihood of a sharp slowdown in the economy.