Stock index futures fell on Sunday as investors reacted to the worsening situation in Japan.

S&P 500 futures were down 7 points to 1292.80. Dow Jones industrial average futures fell 51 points, and Nasdaq 100 futures dropped 17 points.

Japan battled on Monday to prevent a nuclear catastrophe and to care for millions of people without power or water after a massive earthquake and tsunami was feared to have killed more than 10,000 people.

The devastation in Japan could worsen the negative short-term sentiment gripping a vulnerable U.S. stock market. Likely to take the biggest hits are companies exposed to Japan and the nuclear energy sector.

The disaster brought on a flurry of short bets against Japanese stocks on Friday, and that trend could well accelerate on news of deteriorating conditions in Japan over the weekend.

Officials in Japan confirmed three nuclear reactors were at risk of overheating, raising fears of an uncontrolled radiation leak.

(Reporting by David Gaffen; editing by Gunna Dickson)