By Aditya Kalra and Munsif Vengattil

NEW DELHI (Reuters) -The Indian antitrust body has raided the offices of many global advertising giants, including GroupM, Dentsu and Interpublic Group, and a broadcasters' industry group over alleged price collusion, people with direct knowledge told Reuters on Tuesday.

Officers of the Competition Commission of India searched around 10 locations after it initiated a case against the agencies and top broadcasters over allegedly fixing ad rates and discounts, said one of the sources.

Three other sources with direct knowledge confirmed the names of the entities being raided.

The raids were being carried out in Mumbai, New Delhi and Gurugram, the first source said.

Reuters was first to report the enforcement action and details of the antitrust case involving the media agencies.

The raids come as the ad landscape in India is seeing major shifts following the $8.5 billion merger between Walt Disney and Reliance's India media assets, which Jefferies analysts say will have a 40% share of the ad market in TV and streaming segments.

Spokespersons for ad giant GroupM, owned by Britain's WPP, U.S.-based Interpublic's IPG Mediabrands unit, and Japan's Dentsu did not respond to requests for comment.

The Indian Broadcasting and Digital Foundation also did not respond, and neither did the competition commission, which does not make public the details of its enforcement action or cases related to price collusion.

The first source said the CCI was investigating how ad agencies allegedly colluded with certain broadcasters to fix ad prices while selling them to clients, and discussed discounts.

In such surprise raids, CCI officers typically seize documents and record testimonies of company officials. The investigation is likely to then continue for several months, and the process is kept confidential.

In December, the CCI raided some offices of alcohol giants Pernod Ricard and Anheuser-Busch InBev as it investigated accusations of price collusion with retailers in a southern state.

The Indian Broadcasting foundation represents top domestic broadcasters, including billionaire Mukesh Ambani's Reliance-Disney joint venture and Sony and Zee Entertainment.

Reuters was first to report the enforcement action and details of the antitrust case involving the media agencies.

(Reporting by Aditya Kalra and Munsif Vengattil; Editing by Bernadette Baum)