* Futures down: Dow 100 pts, S&P 15 pts, Nasdaq 35 pts
NEW YORK, Dec 16 (Reuters) - U.S. stock index futures fell on Tuesday as a slide in the Russian rouble and crude oil prices sent traders fleeing risky assets.
* The rouble lost more than 17 percent against the U.S. dollar even after Moscow's central bank hiked its main interest rate to 17 percent from 10.5 percent.
* Brent crude lost nearly 4 percent after hitting a low of $58.50 and U.S. crude was down 3 percent at $54.21 after hitting $53.80.
* Adding to global concerns, data showed factory activity shrinking in China and euro zone business growth remaining weak.
* Plunging oil prices could heighten geopolitical tensions, trigger defaults by U.S. shale oil and gas firms and destabilize euro zone inflation expectations, the Bank of England warned on Tuesday.
* U.S. data due later in the day include housing starts for November and Markit's gauge of growth in the manufacturing sector.
Futures snapshot at 7:21 a.m. EST (1221 GMT):
* S&P 500 e-minis were down 14.5 points, or 0.73 percent, with 183,494 contracts changing hands.
* Nasdaq 100 e-minis were down 35.25 points, or 0.85 percent, in volume of 15,802 contracts.
* Dow e-minis were down 100 points, or 0.58 percent, with 15,791 contracts changing hands. (Reporting by Rodrigo Campos; Editing by Chizu Nomiyama)