UPDATE 1-Vivendi buys TF1's pay-TV stake for 744 mln eur

* Vivendi to buy TF1's 10 pct stake in Canal Plus France

* Vivendi and TF1 agreed price 744 mln euros

* Deal comes before TF1's Feb. put option at 747.5 mln

* Vivendi also offered to buy M6's 5.1 pct on same terms (Adds details, background, analyst quote)

PARIS, Nov 23 (Reuters) - Europe's biggest entertainment group Vivendi (VIV.PA) tightened its grip over its pay-TV unit Canal Plus France by agreeing to buy a 9.9 percent stake held by French broadcaster TF1 TFPP.PA for 744 million euros ($1.11 billion).

Vivendi also offered to buy another 5.1 percent holding in Canal Plus France owned by French TV group M6 (MMTP.PA), using the same valuation as the TF1 deal.

Vivendi's offer, which the French group said stood until Dec. 31, values Canal Plus France at roughly the same price as TF1's and M6's put options, which were effective as of February.

M6's put option price stood at 384.2 million euros while TF1's could sell its stake for 747.5 million euros.

Buying TF1's stake would bring Vivendi's ownership of Canal Plus France to 74.9 percent and if it took on M6's stake, that would increase to 80 percent. A Vivendi spokeswoman said M6 had not replied yet about the French group's offer.