FILE PHOTO: International Monetary Fund (IMF) logo is seen outside the headquarters building in Washington, U.S., as IMF Managing Director Christine Lagarde meets with Argentine Treasury Minister Nicolas Dujovne September 4, 2018. REUTERS/Yuri Gripas/File Photo

WASHINGTON (Reuters) - The growing market power of a small fraction of companies in wealthy countries could crimp investment and hurt workers, the International Monetary Fund said on Wednesday, as the growing role of tech giants like Google fuels debate about regulation of the industry.

The IMF did not name names in its latest World Economic Outlook, but said interest in the problem has mounted amid the rise of the tech industry.

“Further increases in the market power of these already-powerful firms could weaken investment, deter innovation, reduce labor income shares, and make it more difficult for monetary policy to stabilize output,” the IMF said.

The report comes just weeks after the U.S. Democratic senator and presidential candidate Elizabeth Warren vowed to break up Amazon.com Inc, Facebook Inc and Alphabet Inc’s Google. She has proposed legislation that would require tech companies that offer online marketplaces to refrain from competing on their own platform and promised to nominate regulators who would unwind acquisitions like Facebook’s deal for WhatsApp and Instagram.

The IMF said the evidence for a “moderate” rise in corporate market power in advanced economies lies in increasing mark-ups charged by a small fraction of companies. While the impact has been modest so far, “it could grow increasingly negative” if dominance of the high-mark-up firms rises further.

“With mounting risks of adverse growth and income distribution effects from rising corporate market power, policymakers should keep future market competition strong,” the IMF said.

The fund stopped short of recommending a breakup of large companies, but advocated for slashing domestic barriers to entry, changing competition policy, and easing obstacles to technological catch-up by lagging firms.