(REUTERS) -- Stock index futures fell on Tuesday on renewed concerns that Greece and private bondholders would not meet a looming deadline to complete a debt swap, potentially opening the way for a messy default that could hurt neighboring economies.

A group representing bondholders warned a default could leave Italy and Spain needing outside help to stop contagion from spreading and cause more than 1 trillion euros ($1.3 trillion) of damage to the region.

Creditors have until Thursday night to accept a bond swap in which they would lose almost three-quarters of the value of their bonds.

Heightening tensions over Greece come a day after China cut its growth forecast and data showed the European Union is unlikely to avoid a recession.

With the fresh uncertainties coming into play about Greece and after the effects of the Chinese slowdown, investors are taking a defensive posture, said Andre Bakhos, director of market analytics at Lek Securities in New York.

Banks and materials shares, sensitive to flare-ups in Europe's debt crisis, fell in early trading. Bank of America Corp lost 1.3 percent to $7.87, while aluminum producer Alcoa Inc was off 1.3 pct to $9.74.

S&P 500 futures were off 10.4 points and below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures slid 81 points, and Nasdaq 100 futures lost 18.5 points.

Greece has no plans to extend the March 8 deadline on its bond swap offer to private creditors, Greek officials said, dismissing market rumors the cutoff date may be changed to increase participation in the offer.

European shares hit a 1-week low. The FTSEurofirst 300 index of top European shares was down 1.2 percent. Hong Kong shares suffered their biggest slump in nearly three months as the Hang Seng index lost 2.2 percent.

Oil eased in volatile trading on concerns over global economic growth despite the continued risk to supplies due to tensions associated with Iran. Brent crude fell 0.5 percent to $123.12 a barrel.

Shares in Exxon Mobil Corp. fell 0.8 percent to $86.30 in premarket trade. The Select Sector SPDR energy exchange-traded fund lost 0.8 percent to $73.70.

Yahoo Inc.'s new chief executive was preparing a significant restructuring of the Internet media company that would include thousands of layoffs, according to a technology blog.

El Paso Corp. delayed a shareholder vote on the pipeline company's acquisition by rival Kinder Morgan Inc to allow investors to consider a judge's ruling that criticized some of the deal's participants.

General Motors Co. will pay 320 million euros ($423 million) for a 7 percent stake in French automaker Peugeot SA as part of an alliance designed to save the companies at least $2 billion.

(Reporting by Edward Krudy; editing by Jeffrey Benkoe)