LONDON, United Kingdom — Core profit margins at Yoox Net-A-Porter (YNAP) will rise by 30 to 70 basis points in 2018 and growth at the luxury online retailer will be boosted by mobile sales and those in the Middle East, the group's chief executive said on Tuesday.

"(The results) in 2017 and the outlook for 2018 put us on track to meet our five-year plan target and we expect an improvement in adjusted EBITDA margin between 30-70 basis points this year," CEO Federico Marchetti told Reuters in an interview ahead of the group's full-year results.

The online retailer, which runs four different websites as well as online flagship stores for famous fashion brands such as Armani, Moncler and Valentino, has set a goal of increasing revenue annually by 17 to 20 percent at constant exchange rates in the years to 2020.

The group said in a statement that full-year adjusted earnings before interest, taxes, depreciation and amortisation (EBITDA) were 169.2 million euros last year, with an EBITDA margin of 8.1 percent.

Marchetti said the group sees a lot of growth coming from mobile sales, "a key pillar of our strategy," with mobile apps as the fastest growing channel within mobile sales.

"We are investing more money in upgrading and redesigning our apps and we will continue with growth (in mobile sales) month after month," Marchetti added.

In January, the group said that in 2017, for the first year, sales by customers shopping with their phone were just above 50 percent of sales.

Just over half of customers buying luxury clothes and accessories online use their mobile for their internet shopping, according to a recent survey by Boston Consulting Group.

That percentage grows to 75 percent for younger customers and 77 percent for those in China, the survey said.

By Giulia Segreti; editor: Adrian Croft.