"The EFTA Surveillance Authority (ESA) and the Norwegian Competition Authority have today initiated an investigation against Telenor Norge AS and Telenor ASA regarding possible abuse of dominant market position and/or possible anti-competitive practices," Telenor said in a statement.
"The investigation is carried out pursuant to Articles 53 and 54 of the EEA Agreement and comprises mobile communication services at wholesale and retail level in Norway, including voice, SMS, MMS and data, as well as mobile services sold in bundles that include other products /services," it added.
Telenor is also the majority stakeholder in Indian telecom operator, Uninor.
Telenor said it has strict internal rules and procedures on compliance with laws and regulations.
"Telenor will co-operate with the authorities in carrying out the investigation so that it can be conducted in an efficient manner. Besides this, Telenor has currently no further comments on this issue," the company said.
Telenor Group has mobile operations in 11 markets in the Nordic region, Central and Eastern Europe and in Asia, as well as a voting stake of 42.95 per cent (economic stake 35.7 per cent) in VimpelCom which operates in 18 markets.
The Norway-headquartered Telenor Group is among world's major mobile operators with 149 million mobile subscribers.