China's largest online travel agency Ctrip will buy British flight search app Skyscanner for $1.7 billion, the companies said, as it steps up its overseas ambitions.

The travel service provider will pay 1.4 billion pounds mainly cash for the Edinburgh-based firm, they said in separate statements late Wednesday.

NASDAQ-listed Ctrip, partly owned by Chinese search giant Baidu, provides online booking for airline and railway tickets as well as hotels, and describes itself as China's largest travel company.

It generated more than 350 billion yuan ($51 billion) in gross merchandise value last year, the firm said on its website, referring to a measure of online sales.

Gareth Williams, chief executive of Skyscanner, said: "Ctrip is the clear market leader in China and a company we can learn a huge amount from."

The acquisition by Ctrip took Skyscanner "one step closer to our goal of making travel search as simple as possible for travellers around the world", he added.

Skyscanner provides similar services to Ctrip and has 60 million monthly active users, mainly in Europe.

Ctrip co-founder and executive chairman Liang Jianzhang said: "This acquisition will strengthen long-term growth drivers for both companies. Skyscanner will complement our positioning at a global scale."

Skyscanner will remain operationally independent with its current management team, the statements said.

Shanghai-based Ctrip merged with another major Chinese online agency Qunar last year to create the country's biggest internet travel service.

The deal gave Baidu, which controlled Qunar, a 25 percent stake in Ctrip.

The Skyscanner deal, already approved by boards of both firms, is still subject to customary closing conditions and is expected to be completed by the end of 2016.

Ctrip closed down 2.10 percent to $40.99 on Wednesday before the announcement.