British retail magnate Sir Phillip Green has sold a 25 per cent stake in his Topshop empire to the US-based owner of J. Crew for £500 million ($751 million).

The sale values the Topshop/Topman brand at £2 billion ($3 billion) and will be used significantly ramp up its expansion into the US and other global markets.

Green now plans to spend the next three to four years doubling the size of the fast fashion chain globally, he said in a Bloomberg TV interview in December.

The sale was confirmed at the end of 2012 between Green and the American private equity group, Leonard Green & Partners (LGP), which co-owns fashion brand J. Crew.

It is the first time that the Monaco-based icon has sold a stake in his empire, which he founded in 1964 and has since built up to 450 stores in over 30 countries.

Green said in a statement that the funds would be reinvested into the brand’s parent company, Arcadia Group, which is now “debt free” due to the sale.

“Being debt free gives us the balance sheet and flexibility to look at other opportunities to consolidate or acquire, either on our own or in partnership with LGP,” he said.

Topshop first entered Australia at the end of 2011 with a store on Melbourne’s famous Chapel St shopping strip.

It has since opened a second store in Sydney and will add a third to the stable this year at Melbourne’s Highpoint Shopping Centre.

As well as being a co-owner of J. Crew, which has over 300 stores in the US, LGP has stakes in Whole Foods Market, Neiman Marcus, Petco and The Container Store.

The sale signals a new frontier for Topshop/Topman in the US, which currently has four stores opened since 2009.

Green said he now has plans for 20 more American outlets in concession spaces at Nordstrom department stores nationally.