Qatar Investment Authority is partly financing Swiss travel retailer Dufry's 1.3 billion-euro purchase of a majority stake in smaller Italian rival World Duty Free, according to three sources close to the matter.

Edizione, the holding company owned by the Benetton family that controls World Duty Free (WDF), said it was selling its 50.1 percent stake in the group to Dufry for 10.25 euros per share.

The deal values the Italian firm at 3.6 billion euros ($3.8 billion) and will make the combined group the world's biggest travel retailer by far.

Edizione said in its statement Dufry would have to carry out a capital increase to partly fund the deal, without elaborating.

Three sources close to the matter said Qatar Investment Authority (QIA) would buy Dufry shares as part of the deal, confirming a report by Reuters that it had teamed up with the Swiss group for the purchase.

One of the sources said QIA would buy 500 million euros' worth of new Dufry shares to be issued as part of the Swiss group's efforts to finance the acquisition. QIA and Dufry both declined to comment.

Edizione said that after buying the 50.1 percent stake from the Benettons, Dufry would launch a takeover bid on the remaining World Duty Free shares -- something that is mandatory under Italian law whenever ownership of a company changes hands.