Oil fell back below $50 on Thursday, resuming a downturn that has cut prices 11 percent from record highs and ending a brief rally following President George W. Bush's U.S. election victory. U.S. light crude slid $1.23 to $49.65 a barrel, around $6 down from record highs hit last week. London Brent was down 90 cents at $46.66. Rising crude stocks in the United States and signs that high energy costs are hurting economic growth are gradually eroding a price rally that has lifted prices more than 50 percent this year. "Oil inventories should rise over the next six to nine months and this should eventually ease the extreme tightness in today's oil markets," said Adam Sieminski of Deutsche Bank in a report. "The main forces that we believe will cause prices to fall include weakening global oil demand, rising non-OPEC supply, and growth in both OPEC production and capacity to produce." OPEC has lifted production above 30 million bpd to meet booming oil demand. The cartel produced 30.11 million bpd in October down just 40,000 bpd on the month, a Reuters survey found on Thursday. --More 2335 Local Time 2035 GMT