Competition Commission of India (CCI) Chairman Ashok Chawla said the probe is going on with respect to Bengaluru city.
In April, the watchdog had ordered a detailed probe after it prima-facie found evidence of Ola violating the competition norms.
"An investigation is going on in respect of Bengaluru city. That is at a very preliminary stage... That is specific to the geographic market of Bengaluru but if problem is there in other cities and other information comes to us, certainly we will look into it," Chawla said.
The probe was ordered following a complaint filed by Chennai-based Fast Track Call Cab Pvt Ltd against ANI Technologies Pvt Ltd, which provides taxi services under the Ola brand. The complainant is a rival operating under Fast Track brand.
CCI's investigation arm -- Director General (DG) -- is probing the matter. It would also look into the conduct of officials of Ola.
"It is observed from the material placed on record that the opposite party is spending more money on discounts and incentives (apart from the variable costs it may be incurring) on customers and drivers compared to the revenue it earning," the regulator had said while ordering the detailed probe in April this year.