Subway co-founder Fred DeLuca hands over more responsibility to his younger sister

The billionaire has been fighting leukaemia for almost two years

Fred DeLuca borrowed $1,000 from family friend Peter Buck, to open his first sandwich shop in Bridgeport, Connecticut, in 1965 (Getty)

The co-founder of Subway has given his sister increased responsibility for running the business, as he fights leukaemia.

Fred DeLuca, who has had the disease for around two years, has handed over management of the sandwich chain to Suzanne Greco in all but name, according to the New York Post.

The 67-year-old billionaire is said to have sent a memo to top executives that said all departments will now report to his 59-year-old sibling, whose official title is senior vice president.

A source told the Post: "On paper, she is running Subway."

However, the company said DeLuca remains at the helm of the business. A spokesperson told The Independent: "Fred has and continues to lead the company as he further empowers his team to better position the company for growth. As a family business he has now shared some of that responsibility with Senior VP Suzanne Greco.

"Suzanne, who has been part of the Subway family since the beginning, has been an active member of the management committee and has lead the R&D and Operations teams for years. She also serves as a member of the Board of Directors and Strategic Planning Committee."

The Subway franchise was established in 1965 after DeLuca borrowed $1,000 from family friend Peter Buck, to open his first sandwich shop in Bridgeport, Connecticut.

Subway now has over 43,000 restaurants around the world and this month it opened its 2,000th store in the UK and Ireland. It is the largest single-brand restaurant chain and the largest restaurant operator globally.

There has been uncertainty about who would step into DeLuca’s shoes as he undergoes treatment. Fellow billionaire Buck has already pulled back over the years.

Last year a survey named Subway the third most popular fast-food choice among millennials. But the chain has struggled with falling sales as customers gravitate towards healthier options.