Google Inc. users in the U.S., Japan and other key countries have shifted more than half their Internet searches to handheld devices from personal computers, driving the company's investments in features for mobile gadgets.

The owner of the largest Web search engine has seen the change in 10 countries, according to Jerry Dischler, vice president of search ads, who will discuss the milestone at an event Tuesday for Google's AdWords product lineup. Google also unveiled tools to help advertisers highlight their services next to mobile-query results.

Google, which is grappling with competition in digital ads from Facebook Inc. and Twitter Inc., is expanding services to reach consumers who are increasingly using mobile devices to look up information on a restaurant, connect with friends or view photos. Google's share of mobile advertising will decline to 35 percent this year from 38 percent in 2014, EMarketer Inc. estimates.

"We think it's a real turning point in digital," Dischler said, referring to the shift to mobile searches. "We've seen the trend coming for several years now — and we've been investing ahead of the opportunity."

The new ad tools include features specifically designed for industries using mobile to promote their wares. In automotive, mobile users can see a carousel of car images that show how a vehicle looks with different options — and tap the picture for extra information. People looking up hotels can see a variety of prices and book the location through a partner service.

The Mountain View, California-based company also unveiled a mortgage feature for its Google Compare service in the U.S., which already offers such a tool in the U.K. Prospective home buyers can now get information on interest rates, loan terms and fees.