NEW YORK, Jan 2 (Reuters)

Oil vaulted to a record $100 a barrel on Wednesday as violence in Nigeria, tight energy stockpiles and a weaker dollar triggered a surge of speculative buying, dealers said.

Oil's climb to the psychologically key triple-digit price sent stocks tumbling on Wall Street and darkened an already gloomy economic outlook in the United States, battered by a housing crisis and credit crunch.

"Oil hitting $100 a barrel has sparked some concerns about the consumer and inflation," said Todd Salamone, vice-president of research at Schaeffer's Investment Research.

U.S. crude traded once at $100 a barrel, up $4.02, then eased back to $99.58 by 2:06 EST (1906 GMT). London Brent crude rose $4.04 to $97.89.

"Oil could rise further from here. It's simple supply and demand fundamentals," said Kris Voorspools, energy analyst at Fortis in Brussels.

The White House said it would not open up the emergency crude oil reserve to lower prices, while an OPEC member said the cartel was powerless to bring the market down from its lofty height.

Crude oil prices jumped 58 per cent in 2007, the biggest annual gain this decade. Oil has nearly tripled since 2000 - driven by rising demand in China and other developing countries, tight stockpile levels and geopolitical turmoil.