The key US contract, West Texas Intermediate, declined more than three percent after having gained more than six percent on Thursday. The sizeable jumps had come after Yemen's Houthi rebels struck oil tankers in the Red Sea, potentially opening a new front in the Middle East war. With tech stocks not as predominant in Europe, that region's main stock markets advanced on Friday. Asian stock markets followed the sell-off Thursday on Wall Street as world markets were battered by a perfect storm of the resurgent Middle East war, the spike in oil prices and concerns about the artificial intelligence boom. - Key figures around 2020 GMT -Brent North Sea Crude: DOWN 3.9 percent at $96.78 per barrel