Baidu Inc, China's biggest search engine, is challenging the country's No 1 e-commerce company, Alibaba Group Holding Ltd, by adding services that help shoppers find retail stores and retrieve product information.

Baidu agreed to invest in mapping company IndoorAtlas Ltd, which allows users to find their way through malls and office buildings, the companies said on Wednesday. The search operator also unveiled a headset that can deliver product information to shoppers and a mobile service that makes it easier for consumers to find nearby businesses.

The company's billionaire founder Robin Li is adding the functions to help sell more advertising by connecting mobile phone users with brick-and-mortar businesses. The move comes days after Baidu formed an online shopping venture with Dalian Wanda Group Co Ltd and Tencent Holdings Ltd, Asia's biggest Internet company, intensifying the rivalry with Alibaba.