Crazy in love: Beyoncé steals limelight at Topshop launch

Reporting by Tania Bryer, Writing by Holly Ellyatt
Beyonce teams up with Topshop as group moves in on US

Global retailer Topshop has opened its new flagship store on Fifth Avenue in New York and celebrities Beyoncé and Cara Delevingne were at the launch to give their support to the brand and owner, Philip Green.

In an exclusive interview with CNBC's Tania Bryer, Beyonce said she had been a "huge fan" of the Topshop brand for many years and that she was excited about her forthcoming collaboration with Green to a "global athletic street-wear brand" to be launched Fall 2015. Model Cara Delevigne, who is the face of Topshop's Fall/Winter 2014 advertising campaigns, was also at the launch and told CNBC that Topshop was "an amazing shop with amazing clothes."

Read more: Run the world: Beyoncé's sportswear for Topshop

The brand, which is part of Green's Arcadia group of retailers, has already established a presence in the U.S. retail space with stores in New York (in Soho), Chicago, Los Angeles, Las Vegas and most recently, in San Diego.

Green told CNBC the 40,000 square foot store -- Topshop's second largest flagship in the world -- on one of New York's main shopping thoroughfares was a "landmark moment" -- particularly after challenges posed by opening the store in its coveted central location.

"I think as part of our whole global development this is a very important landmark moment… You go to all these big cities there's a hundred meter stretch where everyone wants to be and you have to wait until you get that opportunity," he told CNBC at the launch party on Tuesday. Some of the clothes on offer were designed purely for the store's location, he added.

The Fifth Avenue store will employ 300 staff and shows what a "big commitment" Topshop is making to the U.S., Green said.

Read more: Topshop sets out its store on 5th Avenue

"I'm not going to tell you the exact figures but we have got to take tens of millions of dollars here to make it work so it's a commitment . We opened in San Diego five days ago we're signed to go to Houston and Atlanta in the next 6 months. So we've put a stake in the ground – let's see how we can grow the business."