Billionaire American investor Wilbur Ross joined a consortium led by Dublin-based Cardinal Asset Management to bid for Irish building society EBS, Ross told CNBC on Wednesday.

State-run EBS is in talks with three private equity groups and bancassurer Irish Life & Permanent . Sources expect two preferred bidders to be chosen by the end of this month and a winner by the end of next.

Asked what his plans with EBS were, Ross, who earlier this year took a stake in New Jersey lender Sun Bancorp and invested millions in entrepreneur Richard Branson's Virgin Money, said: "To buy EBS and reinfuse capital into it."

A source familiar with the deal said however that no winning bid had yet been selected.

"No decision has been taken yet. The process is ongoing," the source, who declined to be named, said.

Officials at EBS were not immediately available for comment.

Sources have said Irish Life and Cardinal have emerged as the two front-runners in the bidding for the state-run building society, which needs to find 775 million euros (643 million pounds) by the end of the year to shore up its capital base.

Selling EBS to a private investor would be a relief to the Irish state which is injecting a combined 28 billion euros into two other state-controlled lenders Anglo Irish Bank and Irish Nationwide Building Society.