Canadian group Thomson Corporation's planned takeover of British financial news and data provider Reuters Group raises concerns the deal could stifle competition, European Union antitrust regulators announced Monday.

The European Commission, Europe's antitrust authority in Brussels, has said it will make its final ruling by February 25 as to whether the £8.7 billion ($17.7 billion, €12.6 billion) deal will adversely affect European competition in the financial information sector, the New York Times reported Tuesday.

AFP reported Monday the commission has until February 28 to make a final decision on the deal.

Thomson and Reuters, along with privately held U.S. group Bloomberg, the parent of Bloomberg News, are current market leaders in selling financial information to the financial services industry, AFP stated in an article.

Neelie Kroes, the competition commissioner, declined to comment on specific aspects of the merger the commission's extended investigation will focus on, the Times reported.

“A second phase would give us the time to find out what we need to come to a proper and balanced decision,” Kroes said, according to the Times.

London-based Reuters employs 2,400 journalists in more than 130 countries. Should the acquisition go through, Thomson's sales would increase to $11 billion, and triple its share in the financial data services market to 34 percent, the Times reported. Toronto-based Thomson owns the TradeWeb bond-trading network and the Westlaw legal database.

The companies have said that after three years of being combined, they expect to save more than $500 million each year.