WH Smith has agreed to buy InMotion for $198 million (£155 million), in an attempt to expand its travel business into the US.

The FTSE 250-listed retailer is buying the US-airport based digital accessories retailer to double the size of its international travel business.

“InMotion is a highly successful pure-play travel retailer in the world’s largest travel retail market,” said WH Smith’s chief executive, Stephen Clarke.

“As the market leader, recognised for its best-in-class customer service, InMotion is well positioned to take advantage of that potential.”

“In addition, InMotion provides us with a scalable platform to launch the WH Smith airport format into the US, the world’s largest travel retail market for news, books and convenience products,” he added.

InMotion has 114 stores across 43 airports with 750 staff. It is the largest airport-based digital accessories retailer in the US.

The travel-arm of the WH Smith business is the strongest performing, with total revenue up 10%.

The group is scaling back on high street operations after a fall in sales.

“During an encouraging second half, the High Street business traded well and we quickly identified the latest trend in the market, becoming a one-stop-shop for all slime related products,” said Clarke.

“Despite this good performance, we are not ignoring the broader challenges on the UK high street and, during the second half, we conducted a business review to ensure our High Street business is fit for purpose now and for the future,” he added.

Earlier this year, WH Smith was voted the worst retailer on the UK High Street in a survey of more than 10,000 consumers.

InMotion’s senior management team will continue to lead the business.

Completion of the acquisition is expected before the end of 2018.

Shares in WH Smith (LON: SMWH) are trading +6,11% in pre-market trading.