CERNOBBIO, Italy, Sept 4 (Reuters) - A buyout of Italian infrastructure group Atlantia by the Benetton family and U.S. fund Blackstone Inc could be completed by the end of the year, Atlantia's chairman said on Sunday.

The bidders proposed a 58 billion euro ($57.7 billion) offer in April to take the airport and motorway operator private but have yet to launch a formal bid pending regulatory clearance.

"We hope to be able to respect the timetable that we have set," Atlantia Chairman Giampiero Massolo told Reuters on the sidelines of the Ambrosetti Forum conference in northern Italy.

The likely scenario was for a bid to be launched in October, with the aim of delisting the business by the end of the year, he added.

He also confirmed that the group was looking at a potential investment in Chicago Skyway, a U.S. highway toll operator owned by Canadian pension funds OMERS and the Canada Pension Plan (CPP) Investment Board.

"It's an interesting asset," Massolo said.

Spain's El Economista newspaper reported in June that Abertis planned to bid for a 66.6% stake in Chicago Skyway in a transaction that would exceed 2.5 billion euros.

Abertis is a toll road operator controlled by Atlantia and Spanish engineering company ACS, which is led by Real Madrid soccer club owner Florentino Perez.

Massolo said that relations remained good with ACS and Perez, who had been involved in a rival buyout offer for Atlantia this year. ($1 = 1.0049 euros) (Reporting by Francesco Zecchini Writing by Keith Weir Editing by David Goodman )