(Reuters) - A 3% drop in British Airways owner IAG led London's FTSE 100 lower on Friday, as doubts about a U.S.-China trade deal halted a five-day winning streak for European markets. The main index was down 0.4% in early trade, with miners and Asia-focused bank HSBC also down after a report that Beijing and Washington's "phase one" trade deal faced opposition on multiple fronts.The FTSE 250 , up more than 1% to a three-week high a on Thursday after two Bank of England policymakers..