London: World oil prices slumped more than 10 percent on Friday, slammed by demand fear after the emergence of a new variant of Covid-19.In late afternoon London trade, New York's WTI crude tumbled 11.3 percent to $69.53 per barrel, while European benchmark Brent North Sea oil retreated 10.2 percent to $73.81.The two contracts briefly sank as low as $68.75 and $73.03 respectively -- levels last seen in mid-September."Crude oil prices have slumped sharply over concerns that this new mutation...