Google also announced improvements to its mobile search interface for general Web search and local and maps search.

Specifically, Google's mobile home page now will feature icons of local businesses that are commonly searched for, like restaurants, coffee shops and bars, to serve as search shortcuts.

Also, the map image with markers for local results now remains fixed at the top of the mobile results page, and it gets refreshed as users scroll down the list of results.

Mobile search traffic on Google has increased by a factor of five in the past two years, so it continues to rise in importance for Google and its users, Singhal said. In the past year, the use of the voice search feature in Google's mobile search has increased sixfold, officials said.