"The European Commission is expected to open a phase two investigation," said one of the people who declined to be named because the EU competition authority's decision is not yet public.

The Commission is conducting a preliminary review of the case until May 8. After that, it will announce the deeper investigation. A phase two probe can take up to 105 working days.

Liberty Global, controlled by billionaire John Malone, is seeking to expand its cable empire in Europe, where there is demand for faster Internet and digital television. Its bid values Ziggo and its debt at around 10 billion euros $13.84 billion (8.23 billion pounds).

(Reporting by Foo Yun Chee; editing by Barbara Lewis)

Stocks treated in this article : ZIGGO, Liberty Global PLC