China's HNA Group Co Ltd has agreed to buy Swiss airline catering firm Gategroup Holdings for US$1.5 billion in cash, as the aviation and shipping conglomerate steps up its global expansion.

The deal adds to a string of overseas acquisitions for privately owned HNA, which include plans announced in February to buy U.S-listed electronics distributor Ingram Micro for US$6 billion and the US$2.5 billion purchase of Irish aircraft lessor Avolon Holdings Ltd last year.

HNA, which operates more than a dozen airlines including its flagship carrier Hainan Airlines Co Ltd, is offering 1.4 billion Swiss francs or 53 Swiss francs per share for all of Gategroup's outstanding shares, a 17 percent premium to the catering firm's last trading price.

Gategroup's board has recommended the offer, the companies said in a joint statement.

HNA plans to delist Gategroup from the Swiss stock exchange. Gategroup will remain headquartered in Switzerland under the leadership of the current management team.

Spurred on by slowing economic growth at home, Chinese companies have been highly acquisitive this year, with announced deal values topping US$87.5 billion so far, compared to a record US$103 billion launched last year.

This year nearly half of all China outbound M&A in value terms has gone into Switzerland, thanks to state-owned China National Chemical Corp's record US$43 billion bid for seeds and pesticides maker Syngenta AG.

Gategroup has hired Credit Suisse as financial advisor and Homburger AG as legal advisor. UBS is acting as financial advisor to HNA and while Bär & Karrer is acting as legal advisor.

HNA's operations spans aviation, infrastructure, real estate, financial services, tourism and logistics.