(Reuters) - Stock index futures rose on Monday after Wall Street's steep decline last week, but the death of North Korea's leader over the weekend and a warning from Fitch about possible credit downgrades kept investors jittery.

North Korean leader Kim Jong-il died of a heart attack while on a train trip, state media reported Monday, sparking immediate concern over who is in control of the closed state and its nuclear program.

Asian stocks dropped after his death was reported, while European shares reversed early losses and edged higher in early morning trade, halting a sharp 1-1/2 week selloff, as investors bought up shares in defensive sectors.

S&P 500 futures rose 6.4 points and were 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 rose 50 points, and Nasdaq 100 futures added 13 points.

Fitch was the latest rating agency to warn it may downgrade European sovereign debt. It said Friday that the ratings of France and six other euro zone countries could be cut as a comprehensive solution to the region's debt crisis was technically and politically beyond reach.

A tax break for 160 million U.S. workers was in doubt in the face of strong opposition from U.S. House of Representatives Republicans who have rejected a two-month extension that was overwhelmingly approved by the Senate over the weekend.

Saudi billionaire investor Prince Alwaleed bin Talal on Monday said he bought a $300 million stake in fast-growing microblogging site Twitter, gaining another foothold in the global media industry.

All Nippon Airways, the first operator of Boeing Co's 787 Dreamliner, will postpone the start of Dreamliner service on some international routes due to a delay in receiving another of the planes. Boeing shares were unchanged in premarket trade.

Procter & Gamble Co, the world's largest maker of household products, has halted full-time hiring for this fiscal year, a company spokeswoman said, confirming an earlier report.

Talks over potential asset sales as part of AT&T Inc's efforts to get approval of its $39 billion purchase of T-Mobile USA have gone cold, the Wall Street Journal reported.

On the macroeconomic side, investors awaited the National Association of Home Builders' December housing market index, due at 10:00 a.m. EST. Economists in a Reuters survey expected the index to be unchanged at 20.

A rally in U.S. stocks fizzled on Friday, leaving major indexes with modest gains, as investors were torn between hope the U.S. economy was improving and fears over Europe's debt crisis.