* Up to 30 percent in new holding company up for sale
* Benettons to select two long-term investment funds
* Bidders include GIC, Canadian and infrastructure funds
By Pamela Barbaglia, Paola Arosio and Andrés González
LONDON/MILAN/MADRID, June 13 (Reuters) - Italy's Benetton family is in talks with long-term investors including Singapore's GIC to sell up to 30 percent in a new holding entity that will handle its stake in Spanish telecom masts group Cellnex, four sources familiar with the deal told Reuters.
The Benettons agreed in March to buy 29.9 percent of Cellnex as part of a deal to purchase toll-road group Abertis in tandem with Spanish builder ACS.
Cellnex, which has a market value of 5.1 billion euros ($6 billion), ranks as Europe's biggest independent towers company and leases wireless networks to customers including Telefonica in Spain, Wind and Iliad in Italy, Bouygues in France and Sunrise in Switzerland.
Singapore's sovereign wealth fund GIC and other infrastructure funds are interested in Cellnex due to its high growth rate, resilient business model and pan-European presence, the sources said.
Goldman Sachs is overseeing the deal, which will see Sintonia, a sub-holding of the Benetton's Edizione Holding empire, establish a new company that will directly control Cellnex, three of the sources said.
The new company will sell 20 to 30 percent of its shares to an investment duo, likely to consist of a sovereign wealth fund and an infrastructure fund, the sources said.
"The plan is at an advanced stage," one source said, adding negotiations with various interested parties were underway.
A deal could be clinched over the summer but it will hinge on the successful completion of the Abertis takeover, which is expected to close in the third quarter.
Edizione Holding and Cellnex declined to comment while GIC was not immediately available for comment.
The Benetton family used Italy's largest motorway operator Atlantia as a vehicle to purchase Abertis -- which controls Cellnex -- and later reorganised the Abertis and Cellnex interests' into different holdings, the sources said.
Canadian pension funds have also expressed interest in Cellnex alongside other infrastructure investors, the sources said, with one adding a Japanese bidder was also in the fray.
The Benettons have a history of working with sovereign wealth funds and particularly Singapore's GIC which holds an 8.14 percent stake in Atlantia and was previously invested in Sintonia.
The family held extensive talks with infrastructure investors last year when it sold an 11.94 percent stake in their motorway unit Autostrade per l'Italia (ASPI). Part of the ASPI stake went to a consortium comprising Allianz Capital Partners, EDF Investment and fund DIF Infrastructure while China's Silk Road Fund purchased another 5 percent.
The sources said some of the same infrastructure funds that were eyeing the ASPI deal are now taking a closer look at Cellnex, whose headquarters was moved from Barcelona to Madrid last year during the Catalonia crisis.
Cellnex has been building scale across Europe through a series of mergers and acquisitions (M&A) deals involving the likes of France's Bouygues Telecom and the Benettons intend to continue using M&A to extract further growth, the sources said.
Cellnex, led by boss Tobias Martinez Gimeno, operates in Spain, France, Italy, Switzerland, Britain and the Netherlands. Its revenue grew 12 percent last year to 789 million euros while its adjusted earnings went up 22 percent to 355 million euros. ($1 = 0.8508 euros) (Reporting By Pamela Barbaglia)