The World Association of Newspapers (WAN) said it opposes a pending deal on advertising between Yahoo and Google.
An Associated Press report quoted the Paris-based group saying it wants European and US regulators to block the deal on antitrust grounds.
WAN says the agreement would reduce the cost of paid search advertising and lower revenues for newspapers' and others' web sites, which receive payment from the online giants.
WAN says it fears the deal would give Google 'unwarranted' market power in parts of the online ad business. Yahoo expects the deal to generate millions in annual revenue.
Yahoo and Google say the deal only affects North America, but WAN alleged that European newspapers would be affected, the Associated Press report also said.