Topshop's US debut is understood to have been put back to spring 2009 because of construction problems at its New York site.
Topshop's New York launch had already been put back a month to November but the further delay means the 40,000sq ft store on Broadway in New York's SoHo district will not open for several months.
The 2009 launch will come as a blow to the young fashion retailer, as it means it will miss out on the Christmas trading period and will be unable to capitalise on the recent blaze of publicity it has had in the US.
A spokeswoman for Topshop confirmed to Drapers that Green was in the US ironing out problems with contractors and said she could not yet confirm the new opening date.
A source close to the situation said: "It has been difficult to negotiate with the Americans."
A second source said: "It's been put back to spring because Topshop doesn't want to open in the Sale period after Christmas or in the likely bad weather in January and February."
Topshop launched a transactional website for the US market this month to help build excitement among consumers ahead of the store’s launch.