The group, which makes around a sixth of its total revenue in Britain and is one of the Italian listed companies most exposed to the market, said it is expanding its London headquarters and is hiring several hundred new staff despite Brexit.

"We believe in this market. We believe in London and we continue to grow here," Chief Executive Federico Marchetti told journalists. "We have a very resilient business model thanks to our geographies being global."

YNAP said it planned to more than double revenues to around 4 billion euros (3.38 billion pounds) by 2020 and increase its group adjusted core profit margin to around 11 to 13 percent from 8 percent last year.

YNAP shares rose 5 percent after the business plan was initially released but were down 3.4 percent by 0950 GMT, compared to a 1.8 percent fall for Milan's blue-chip index <.FTMIB>.

YNAP will launch full operations in the Middle East in 2018 and expand further in China and the rest of Asia, while growing in markets such as France, Germany and Russia where Marchetti said it had just "scratched the surface".

The group - in which Swiss watchmaker Richemont (>> Compagnie Financiere Richemont SA) is a major shareholder - also announced plans to offer jewellery and watches, targeting sales of 100 million euros by 2020. Marchetti dismissed doubts that shoppers will buy such pricey items online by saying trials had proved very successful.

That is part of a strategy to focus even more on the highest spending customers and the fastest growing brands online as well as investing heavily in mobile, with three-quarters of sales set to come from mobile devices by 2020 from 41 percent now.

YNAP, born from the merger of Italy's Yoox with upmarket rival Net-A-Porter, has its own multi-brand shopping websites but also operates online stores for luxury brands including Armani and Valentino. It added Prada on Wednesday.

Marchetti shrugged off the threat from Amazon (>> Amazon.com, Inc.) moving into online fashion due to its relationship with high-end customers and brands. "We are uniquely positioned in the high end of online luxury," he said.

Finance chief Enrico Cavatorta said he expected synergies from the merger to take full effect from 2018, improving margins. He said the group should be cash positive from 2018.

He saw the fall in the pound after the Brexit vote as neutral for profitability because the group had well-balanced costs and revenues denominated in sterling. He does not expect any significant impact on profitability from potential future import duty.

Further out, YNAP will be helped to hedge currency risk by a global distribution network that will allow customers to access stock held in other regions and help its brands integrate stock in their stores with online inventory, Cavatorta added.

(Editing by Ruth Pitchford)

By Agnieszka Flak and Emma Thomasson