By Daniel Hunter

Online shopping in the world's four biggest markets is expected to double in size, by £320 billion, over the next three years, according to new research.

A study by PayPal, Google and OC&C Strategy Consultants predicts that online shopping market will be worth £645bn in the UK, US Germany and China by 20018.

In the UK, around £1 in every £15 is spent via the internet and the research found that the every increasingly powerful smartphones will boost mobile shopping.

Nearly 60% of online sales in the UK are done through mobile devices, falling to 45% in the US and 24% in Germany.

It also found that the UK is increasingly becoming the destination of choice for overseas online shoppers. It said that Chinese consumers purchase products from UK retailers almost as often as British shoppers. They are also the most popular for German consumers.

Despite the popularity of British retailers and the frequency of purchases made by UK consumers, other nations are spending more. The Chinese are spending 2.7x more on British purchases than Brits, and German consumers spend 1.7x more.

Anita Balchandani, head of retail at OC&C, said: “The study has shown that UK retailers are some of the world’s most popular and are in a strong position to seize more opportunities abroad.

“But at the moment, the majority are only doing the basics to adequately serve foreign markets, for example, by offering international delivery on their UK website and working with partners to provide local returns addresses.”

Martijn Bertisen, sales director at Google UK, said: “The number of people with internet access is growing fast, with many new consumers skipping the desktop phase entirely and only experiencing the web through a smartphone.

“Our study shows that this is increasingly translating into mobile transactions and that a mobile-first or even mobile-only strategy is now imperative to international success in retail. UK retailers should be well positioned to lead this growth internationally, as UK consumers are already amongst the most mobile of all.”