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April 11 (Reuters) - Canada's Competition Bureau said on Friday it has started an investigation into Cigna's CI.N pharmacy services unit Express Scripts' alleged anti-competitive conduct that could prevent or limit competition in the country's drug retail market.

The agency said it is looking into Express Scripts' alleged "patient steering" to make people use pharmacies owned or associated with its Canada unit, instead of a drugstore of the patient's choice.

The bureau is also looking into practices that are reducing the margins of its retail pharmacies.

Cigna did not immediately respond to a Reuters request for comment.

Express Scripts has the largest pharmacy benefit management operations in Canada, according to the Canadian Pharmacists Association (CPhA).

The association had last year filed a complaint with the antitrust agency alleging "longstanding and exploitative practices" by the company. It was not clear if the probe was due to the CPhA's complaint.

Express Scripts provides prescription drug claim processing and other services for insurance providers and pharmacists and operates four mail-order pharmacies across Canada, except for Quebec, according to the agency.

The agency said an order granted by the federal court requires Express Scripts Canada to produce records and written information, and provide oral testimony, that are relevant to its investigation.

There is no conclusion of wrongdoing at this time, the bureau said.

(Reporting by Sneha S K in Bengaluru; Editing by Leroy Leo)

((Sneha.SK@thomsonreuters.com))