The EU is expected to set out later the action it will take against Google over alleged anti-competitive behaviour.
Margrethe Vestager, the competition commissioner, could make a statement about her intentions on Wednesday.
Reports suggest she will announce that a "statement of objections" is being prepared.
Such action would mark an escalation in the Commission's handling of complaints that Google favours its own products in search engine results.
Google accounts for more than a 90% share of EU-based web searches.
The company has yet to respond.