U.S. stock index futures rose on Thursday as investors looked for buying opportunities after a sell-off that has driven the S&P 500 down 3 percent for the week.

U.S. stocks sagged Wednesday as civil unrest intensified in Greece and fears grew that the Greek debt crisis could spread to other European economies. The euro hit a 14-month low as investors shunned the debt of weaker euro zone countries and jumped into safe havens like U.S. Treasury prices and the dollar.

Investors will focus on weekly first-time claims for jobless benefits due from the Labor Department at 8:30 a.m. EDT. Economists in a Reuters survey forecast a total of 440,000 new claims, compared with 448,000 in the prior week.

The Labor Department also releases preliminary first-quarter productivity and unit labor cost data at 8:30 a.m. EDT. Economists look for a rise of 2.5 percent in productivity versus a 6.9 percent increase in the prior period. Unit labor costs are expected to fall 0.7 percent compared with a 5.9 decline in the previous report.

Kraft Foods Inc is due to report quarterly results, and analysts expect earnings of 45 cents per share, unchanged from a year ago, according to Thomson Reuters

S&P 500 futures were up 2.9 points and above 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 gained 20 points, while Nasdaq 100 futures rose 2.75 points.

German Chancellor Angela Merkel said Wednesday Europe's fate was at stake, while France declared the euro was under speculative attack but that the attempts would fail. The Greek government vowed not to retreat a single step despite violent protests against the government's plan to force spending cuts.

The European Central Bank will be under pressure on Thursday to show it can stop the Greek crisis from engulfing other euro zone member states. The central bank is expected to hold rates at a record low of 1.0 percent.

Britons voted on Thursday in what looks like the closest election since 1992. At stake is how the British economy can recover from recession, and if the next government will reduce a huge budget deficit to slow an upward spiral in the nation's debt.

Oil workers, volunteers and the military prepared to toil for another day in the Gulf of Mexico to plug a gushing oil leak and protect the U.S. coast from an environmental nightmare.

The U.S. Securities and Exchange Commission is looking into disclosures made by billionaire investor Warren Buffett's Berkshire Hathaway Inc as it sought to purchase Burlington Northern Santa Fe Corp, the Wall Street Journal reported, citing sources.

BNP Paribas revealed a $6.7 billion exposure to Greece, the largest among major French banks, as worries over contagion from Greece kept lenders under pressure. The bank posted a profit that beat estimates on improved market conditions and the integration of Fortis, and said the economic recovery had begun.

(Reporting by Angela Moon; editing by Jeffrey Benkoe)