Stock index futures rose on Thursday as investors shifted focus to jobs data later in the morning, temporarily brushing off euro zone debt concerns.

But futures volume remaining light, suggesting optimism was limited in scope, and analysts said the market could easily reverse course back to the downside.

We are at the quarter end, and the fact that we've had a good earnings season, continued expansion of the economy and also relatively cheap valuation (in stocks) looking forward is helping the market, said Peter Kenny, managing director at Knight Equity Markets in New Jersey.

But the extremely light volume is making it very easy for the market to gain or lose.

Best Buy Co Inc shares rose 5.9 percent to $33.80 in premarket trade after it reported results.

The Labor Department releases first-time claims for jobless benefits for the week ended March 19 at 8:30 a.m. EDT. Economists in a Reuters survey forecast a total of 383,000 new filings, compared with 385,000 in the prior week.

Portuguese Prime Minister Jose Socrates resigned and warned of grave consequences for the country after parliament rejected his government's latest austerity measures aimed at avoiding a bailout. The resignation increased expectations Lisbon will seek international aid. It also threw into disarray a European Union summit later this week expected to address the region's debt crisis.

S&P 500 futures were up 10.3 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 82 points, and Nasdaq 100 futures rose 22 points.

Oracle Corp is due to report results later in the day and offer any evidence of the upward curve of technology spending.

The Commerce Department will release February durable goods orders data at 8:30 a.m. EDT. Economists expect a rise of 1.1 percent versus a 3.2 percent increase in January.

Rating agency Moody's downgraded its ratings for 30 Spanish banks by one or more notches, citing a weak outlook with no major improvement in sight. The agency cut Spain sovereign debt rating on March 10.

Western warplanes hit Libya for a fifth night, but have failed to stop Muammar Gaddafi's tanks from shelling rebel-held towns.

Stores in Tokyo were running out of bottled water after radiation from a damaged nuclear complex briefly made tap water unsafe for babies, while more nations curbed imports of Japanese food.

Global stocks inched up and were now higher than when Japan's earthquake and tsunami struck, buoyed by confidence that the world economic recovery remains on track. The MSCI All-Country index has recouped losses since March 11.

(Reporting by Angela Moon; editing by Jeffrey Benkoe)