* CEO Donnet elected for third term

* Rebel investor Caltagirone's camp wins three board seats

* Company had faced criticism over growth plans

MILAN, April 29 (Reuters) - Philippe Donnet kept his job as chief executive of Italian insurer Generali on Friday, surviving a challenge from rebel domestic investors who retained board seats and vowed to keep up the pressure for reform.

The vote at the company's annual general meeting (AGM) followed months of bitter infighting at the heart of Europe's third-largest insurer and leaves a question mark over whether his main opponents will hang on to their combined 20% stake.

Donnet called for unity after seeing off a challenge spearheaded by investor Francesco Gaetano Caltagirone and backed by his fellow billionaire Leonardo Del Vecchio who were advocating for faster growth including through acquisitions.

Italy's Benetton family has also sided with the rebels.

"The unambiguous choice of a majority of shareholders is proof of the confidence they have in our management team and strategic plan," said Donnet, who enjoyed the backing of leading investor Mediobanca and Generali's institutional shareholders including large foreign funds.

"Now we'll all work together in one direction with the board, management and our network of agents ... to pursue the interest of all stakeholders and the success of our group."

Caltagirone put up a rival set of candidates to those proposed by the Generali board. His share of the vote was enough to give his list three seats on the 13-strong Generali board, potentially making life uncomfortable for Donnet, who has been in charge since 2016.

PUSHING FOR CHANGE

Caltagirone said he would still seek reform and added that foreign investors might not have fully grasped the need to revamp the insurer.

"I will continue to work so that changes take place for as long as I deem reasonable to do so," he said in a statement.

The company's board nominees gained the support of almost 56% of shareholders who voted at the AGM, against 42% for the Caltagirone slate.

"A board elected with 55% of votes cannot but take into account the remaining 45%," Caltagirone added.

Caltagirone, a construction and media entrepreneur, will be in line to return to the board because his was the first name on the slate put forward by his group.

A director at Generali since 2007, Caltagirone had quit his seat in January after rejecting the multi-year strategy Donnet presented the previous month.

Caltagirone had nominated former Generali executive Luciano Cirina as a replacement for Donnet and former Goldman Sachs banker Claudio Costamagna as chairman alongside Cirina.

Cirina and Costamagna had dubbed their program "Awakening the Lion," a reference to Generali's nickname "The Lion of Trieste."

They wanted to spend as much as 7 billion euros ($7.4 billion) on M&A, compared with the existing board's plan for 3 billion euros, and had also targeted annual earnings growth of more than 14% with heavy cost cuts and acquisitions.

Roberto Lottici, a fund manager at Banca Ifigest in Milan, said it was vital that the rival parties establish a dialog.

"The challenge will be to combine Generali's trademark 'safety and solidity' with the bolder attitude promoted by Caltagirone," Lottici said. ($1 = 0.9462 euros) (Additional reporting by Stefano Bernabei; Editing by Keith Weir, David Goodman and Louise Heavens)