Clearest sign yet that fresh competition charges likely Getty ImagesMargrethe Vestager, EU commissioner for competition, show speaking in April in Washington, D.C.European Union regulators will actively pursue Google parent Alphabet Inc. on multiple fronts ranging from its contracts with advertisers to its Android mobile-operating system, the bloc’s antitrust chief Margrethe Vestager said, in the clearest sign yet that the U.S. search giant is likely to face fresh competition charges in Brussels. In an interview, Ms. Vestager also hinted that a compromise is possible with Russian energy company OAO Gazprom, OGZD, -2.21% which the EU has charged with hindering competition in Eastern European gas markets, and expressed skepticism over claims that Europe’s telecommunications operators need to merge. A year after taking office as Europe’s most powerful regulator, Ms. Vestager has moved decisively on a number of major cases that had languished under her predecessor, Joaquín Almunia of Spain. She has shaken the corporate world several times in her first year, most recently last week with twin decisions, one affecting Starbucks Corp. SBUX, +1.31% that cast doubt on thousands of tax structures and launching a sweeping inquiry into online commerce that has embroiled Amazon.com Inc. AMZN, +1.60% and others. But she has also played a deft hand, flying to the U.S. immediately after her Google GOOG, +1.54% GOOGL, +1.64% decision in April to defend that action publicly, and waving through large mergers for General Electric Co. GE, +0.14%and FedEx Corp. FDX, -1.03% that had initially raised concerns. Above all, Google’s owner has found itself in the new commissioner’s cross hairs. In April, Ms. Vestager became the first antitrust regulator globally to file formal charges against the U.S. search giant. An expanded version of this report appears at WSJ.com.