* Canal Plus and Havas arm implicated in this plan

* Also investment arm that holds its Lagardere stake

* Vivendi says it has suffered 'conglomerate discount'

PARIS, Dec 13 (Reuters) - French media company Vivendi said it had decided to examine splitting up some of its activities into several entities, each of which would then be listed on the stock market, in order to boost their growth and development.

Vivendi - in which France's billionaire Bollore family holds the biggest individual stake - said the businesses that could be spun off in this way included its TV unit Canal Plus, advertising arm Havas and an investment company holding its stake in French company Lagardere.

"The investment company would actively support the strategic development of its portfolio companies and would focus on value creation and capital return to its shareholders, through an effective portfolio rotation and a targeted reinvestment policy," said Vivendi in a statement.

It added that this plan would help it overcome what Vivendi said was a 'high conglomerate discount' regarding its valuation.

In October, Vivendi had reported a

rise in its third quarter revenues

, driven by growth at Canal Plus and Havas.

Vivendi is also the biggest shareholder in Telecom Italia. Vivendi is expected to

challenge legally Telecom Italia

's 19 billion euros ($20.7 billion) sale of its prized fixed-line grid to U.S. fund KKR.

Shares in Vivendi closed up 0.7 percent on Wednesday, giving it a market capitalisation of roughly 9 billion euros.

($1 = 0.9190 euros) (Reporting by Sudip Kar-Gupta; editing by Jonathan Oatis and David Gregorio)