Adds deal details, background, paragraphs 4-5, 7-8

March 2 (Reuters) - Real estate income trust Welltower WELL.N is set to expand its operations in Canada by acquiring luxury senior homes operator Amica Senior Lifestyles' portfolio from the Ontario Teachers' Pension Plan for C$4.6 billion ($3.18 billion), Welltower said on Sunday.

As part of the deal, Welltower said it will assume C$560 million in Canada Mortgage and Housing Corp insured debt.

The portfolio from Amica consists of 38 luxury seniors-housing communities, 9 entitled development parcels, including a 31-property in-place portfolio, Welltower said.

The REIT will also form a long-term partnership with Amica's management by acquiring minority interest in the private-pay retirement residences firm's management company, it said in a statement.

Welltower said that apart from the in-place portfolio, it also will acquire seven properties currently under construction that are expected to be completed between 2025 and 2027.

In 2015, Ontario Teachers -- one of the world's largest pension plans -- through its BayBridge unit took Amica Mature Lifestyles private for C$578 million and merged it with its seniors-housing subsidiary to create Amica Senior Lifestyles.

Established in 1996, Amica owns and operates over 30 residences in British Columbia and Ontario, according to its website.

The deal would further expand Ohio-based Welltower's operations in Canada. It already has a presence in the United States, Canada and the UK, where it owns housing, outpatient medical centers and healthcare properties with a focus on older adults and assisted living.

Welltower said it expects the deal to close in the fourth quarter of 2025.

($1 = 1.4448 Canadian dollars)

(Reporting by Bipasha Dey in Bengaluru; additional reporting by Gursimran Kaur, Editing by Lisa Shumaker and Bill Berkrot)

((Bipasha.Dey@thomsonreuters.com;))