Canal+ owner Vivendi, which already owns 27% of Lagardere, said it had agreed to buy Amber Capital's 17.9% holding for 24.10 euros per share, or about 610 million euros ($718.95 million).

Vivendi said it would later launch a full bid at the same price once it has passed the 30% threshold requiring companies in France to make a takeover offer.

"We believe Vivendi is primarily interested in Lagardere's International Publishing business which would bring scale, synergies & savings to Editis", analysts at JP Morgan said in a note.

They also said that Vivendi would likely seek to sell the travel retail business to fund the acquisition.

If successful, the acquisition of Lagardere will mark the end of what was once one of France's national industrial champions, which under its late founder used to have large stakes in companies like plane maker Airbus.

Heir and Chief Executive Arnaud Lagardere has sold off parts of the conglomerate bit by bit. Last year he brought in investors like Vivendi and luxury goods tycoon Bernard Arnault when he was trying to fend off an activist campaign by Amber Capital.

($1 = 0.8485 euros)

(Reporting by Matthieu Protard, Sudip Kar-Gupta and Marc Angrand; Editing by David Goodman and Emelia Sithole-Matarise)