(Reuters) - U.S. property and casualty insurance company Hanover Insurance Group Inc (>> Hanover Insurance Group Inc) has hired former health insurer Aetna Inc (>> Aetna Inc) chief financial officer Joseph Zubretsky as its new chief executive officer, people familiar with the matter said.

Zubretsky's appointment comes as the Worcester, Massachusetts-based company has been raising prices to maintain its profitability in the face of lower investment returns in its portfolio and a rise in claims in certain sectors.

Hanover Insurance could announce Zubretsky's new role as early as Monday, the people said on Sunday, asking not to be identified because the matter is still not public. Hanover Insurance offered no immediate comment.

With a market capitalization of $3.7 billion, Hanover Insurance offers insurance protection for homes, automobiles, and other personal items to consumers and businesses. Hanover Insurance also underwrites business at Lloyd's of London in the marine, casualty and energy sectors.

Hanover Insurance's previous CEO, Fred Eppinger, announced in September he would step down to pursue other interests once a successor had been named. In October, Hanover Insurance CFO David Greenfield passed away suddenly.

Executive headhunting firm Heidrick & Struggles International Inc (>> Heidrick & Struggles International, Inc.) was brought in November to help with the new CEO search.

Having taken over as CEO in 2003, Eppinger transformed Hanover Insurance from a regional life insurer to one of the largest, and much more diversified, U.S. casualty and property insurance companies. Zubretsky now faces the challenge of once again reinventing the company in a much more competitive landscape.

Zubretsky, 59, left Aetna last year after nine years with the company in several senior roles, including CFO and leader of Healthagen, a division that combined the health management and information technology companies that Aetna had acquired in recent years.

Hanover Insurance's board was looking for a CEO who can grow the company further through acquisitions, according to one of the sources. Several of Hanover Insurance's larger peers have agreed to merge recently.

Swiss insurance giant ACE Ltd acquired U.S. property insurer Chubb Corp in January for 29.5 billion, while Tokio Marine Holdings Inc (>> Tokio Marine Holdings Inc), Japan's biggest insurer by market value, bought HCC Insurance Holdings last year for $7.5 billion.

Prior to joining Aetna, Zubretsky was the CFO of Unum Group (>> Unum Group), a Chattanooga, Tennessee-based insurer that provides disability, life, accident and critical illness coverage.

(Reporting by Mike Stone in New York; Editing by Chris Reese & Shri Navaratnam)

By Mike Stone