General Electric (GE) may have to put forward stronger concessions to bag EU approval for its purchase of Alstom's power unit, as regulators reportedly plan to warn the US conglomerate that its bid will hurt competition.
GE's planned €12.4bn (£9bn, $13.93bn) acquisition of Alstom's power equipment business, the biggest deal in its history, has received the green light in Brazil, South Africa and India.
But the European Commission (EC) could put out "a statement of objections" on 12 June, according to Reuters.
The document would list the EU regulator's views on why a deal is seen as anti-competitive and serves as a prelude to a veto, unless the companies come up with strong arguments or significant concessions.
GE is seeking to counter the EC's concerns, the news agency added.
EC spokesman Ricardo Cardoso has refused to comment on the matter, while Alstom had no immediate comment.
GE said it was working constructively with the regulator. "We are focused on a positive outcome that preserves the deal economics," it said, adding it was confident of closing the deal in the second half of 2015.
The news hit Alstom's stock, causing it to drop 5.43% on 11 June.
In May, GE CEO Jeff Immelt said his firm will consider selling intellectual property rights to a product, but not concessions that will affect lucrative service revenues.
In February, the EU competition watchdog said the GE-Alstom deal will leave just two players in Europe, with GE competing only with German rival Siemens. Globally, the third rival will be Mitsubishi Hitachi Power Systems.
In 2001, the EC rejected GE's planned $42bn buyout of Honeywell International.