H.I.S. Co., Japan's largest retailer of discount air tickets, will set up a joint company with Sony Corp.'s Internet arm to offer travel services via the Internet from this summer, company sources said Monday.

Tokyo-based H.I.S. is expected to make an announcement on the plan this afternoon, the sources said.

The new company would allow Internet users to book and purchase overseas holidays and air tickets, including discount tickets, 24 hours a day, the sources said.

H.I.S. can expect to expand its business further and reduce sales costs by linking up with Sony Communication Network Corp., known as So-net, an Internet service provider with 1.2 million subscribers, the sources said.

So-net is hoping the tieup will help expand its services.

The new company will be 51 percent owned by H.I.S. and 49 percent by So-net. It will have an initial capitalization of 50 million yen, which will soon be boosted to nearly 500 million yen, the sources said.

Travel services are a huge market in Japan, worth 17 trillion yen annually according to one estimate. However, only an estimated 20 billion yen in services are sold via the Internet.