The planned acquisition of 75% of VOO valuing the company at 1.8 billion euros ($1.82 billion) and announced in November underscores Orange's strategy of offering 'convergent offers' in both broadband and mobile to customers in all European countries.

In recent years the telecoms sector has seen operators embark on packages encompassing both broadband and mobile to entice users and grab market share.

The European Commission's preliminary scrutiny of the deal ends on Thursday, which will immediately trigger a full-scale investigation because Orange did not provide concessions to address its concerns, the person said.

Orange did not immediately respond to a request for comment. The Commission declined to comment.

The VOO deal would give Orange control over the cable network in Belgium's French-speaking Wallonia region and part of the Brussels area, pitting it against rival Telenet.

The French company's Belgian unit Orange Belgium owns its cellular network, but has costly contracts with rivals in order to offer broadband services on top of mobile contracts.

($1 = 0.9866 euros)

(Reporting by Foo Yun Chee; Additional reporting by Mathieu Rosemain in Paris; Editing by Jan Harvey)

By Foo Yun Chee