Google is looking to make it easier for people to shop while using its website, launching a trial run of a feature allowing smartphone users make online purchases from their search results.

The introduction of 'Purchases on Google' comes as Facebook, and Pinterest also try to make it easier for people to shop while using their sites, putting themselves in position to profit from transactions or related advertising.

"Although we're still in early experiments with a limited number of retailers, we see 'Purchases on Google' as a big step towards helping retailers drive more mobile conversions and win more customers," Google shopping product management vice president Jonathan Alferness said in a blog post.

Mobile devices, typically smartphones, are increasingly consulted before or during shopping trips in the United States, influencing nearly a trillion dollars in in-store sales last year, according to Alferness.

When people make shopping-related searches using Google, results may include ads featuring 'Buy on Google' buttons that can be clicked to jump to pages where they can check-out using payment credentials stored in Google accounts.

"Purchases on Google will simplify our customers' ability to search for items on Google and then buy with Staples," Staples executive vice president of global e-commerce Faisal Masud said in the blog post.

Google also rolled out enhancements to shopping ads on mobile devices, including expanded information regarding topics such as product ratings and whether items are available at nearby stores.

"As the consumer continues to rapidly adopt mobile as their primary device, we have to more at a similar pace in how we reduce purchase friction and enhance the user experience with our brand," Under Armour chief revenue officer of digital Jason LaRose said in the blog post.

"Google's technology solutions help us innovate." Pinterest last month dove into e-commerce with "pins" that let iPhone or iPad users in the United States buy items they like at the popular online bulletin board.

"Pinterest is already designed to work like a catalogue, so we wanted to find a way to weave buyable pins into the pages people already know," co-founder and chief executive Ben Silbermann said during a launch event at the company's headquarters in San Francisco.

"Buyable pins are a simple and secure way to buy the products you love right from inside Pinterest," he said.

Pinterest has become one of the Internet's hottest new websites, particularly among women, by giving people virtual bulletin boards that they can decorate with pictures showcasing interests in anything from food to sports, to fashion or travel.

Last month, Facebook expanded tests of a "buy button" designed to let shoppers easily purchases items advertised at the social network.