Google Inc (GOOGL.O) is in early talks to buy Bangalore-based start-up InMobi, in a move that would strengthen its offering in the increasingly competitive mobile advertising space, a source with direct knowledge of the matter said.

InMobi, which helps companies target phones and mobile devices in their advertising, was launched in 2007 and claims to have over 1 billion users across 200 countries. It counts Japan's SoftBank (9984.T), an early backer of China's Alibaba, and early stage venture capital firm Sherpalo among investors.

The source, who asked not to be named because the companies have not made the negotiations public, said talks were at an early stage. The source said Google had not yet detailed its terms and conditions for the deal.

InMobi would likely be valued at around $1 billion, the source said.

The Economic Times newspaper first reported news of these ongoing talks on Wednesday.

Both InMobi and Google declined to comment.