* Board to give recommendation on Bonomi's offer - source
* Bonomi welcomes support from son of Club Med founder
* Club Med trading slightly above the 21 euros offered by Bonomi
By Dominique Vidalon
PARIS, July 21 (Reuters) - Club Mediterranee's board of directors will meet on Friday to decide whether to back a takeover offer for the holidays group from top shareholder Andrea Bonomi, according to a source close to the matter.
"The board will meet July 25 to give a motivated opinion on the offer," the source said on Monday, without providing further details on this latest step in the bid battle for the French resort operator.
Italian tycoon Bonomi is now the largest shareholder in the all-inclusive holidays pioneer, having built a stake of nearly 11 percent this year. He is offering 21 euros a share for Club Med, valuing it at 790 million euros ($1.1 billion).
His offer tops a one year-old 557 million euros offer by China's Fosun International and French private equity group Ardian. That offer was priced at 17.50 euros a share but became mired in legal challenges and shareholder opposition to it as too low.
At 1023 GMT, Club Med shares were up 0.24 percent at 21.30 euros, bringing gains so far this year to 22 percent.
Bonomi must also convince Club Med shareholders, staff and the French establishment his offer is best for Club Med's future. Part of his strategy to win support has been to promise accelerated expansion in France.
On Sunday his offer received the backing of Serge Trigano, the son of Club Mediterranee's founder Gilbert Trigano.
Trigano told French weekly Le Journal Du Dimanche Bonomi's offer was more appealing for shareholders and preserved Club Med's roots in France as well as its lower-cost options.
Trigano would become the resort chain's non-executive chairman if Bonomi's offer is successful.
"The support of Serge Trigano is excellent news," Bonomi said in an e-mail to Reuters, adding it "answered all the questions" raised by his bid and confirmed Club Med's focus on France and respect for its values.
Fosun, with a 9.96 percent stake, and Ardian, with 9.4 percent, have said their plan is to accelerate Club Med's shift towards China, which Club Med wants to make its second-biggest zone after France by 2015.
Bonomi has said he believed the future of Club Med was not solely in China but also in Europe and the Americas. He has also warned against neglecting the cheaper end of the holiday market.
Gaillon Invest, the investment vehicle of the Ardian-Fosun alliance, has so far refused to raise its 17.50 euro offer but has said it will review Bonomi's offer.
Under an indicative calendar provided by Bonomi to French AMF stock market regulator, his offer would start on Aug. 7 and run until Sept. 11.
AMF has yet to provide an official calendar for Bonomi and Gaillon's offers.
(Reporting by Dominique Vidalon, additional reporting by Francesca Landini in Milan; Editing by Andrew Callus)