Oil falls as Brexit threat rattles markets

By Amanda Cooper LONDON (Reuters) - Oil fell on Tuesday, as investor nervousness over next week's vote on Britain's possible European Union exit swept financial markets, eclipsing signs of a return to health for crude prices. Perceived safe-haven assets such as the Swiss franc and German Bunds rallied, while industrial commodities and equity markets, seen as more vulnerable to economic risk, fell after polls showed Britain's "Leave" campaign leading before a referendum on EU membership.. This ov