By Pablo Mayo Cerqueiro, Amy-Jo Crowley and Andres Gonzalez

LONDON, Feb 15 (Reuters) - Dutch insurer Achmea has held early stage discussions about a potential sale of its life insurance operations, including with rivals NN Group NN.AS and Apollo Global Management-backed Athora, four people familiar with the matter told Reuters.

Achmea, an insurance cooperative backed by Rabobank, said this week it was "exploring internal and external options" for its Pension & Life Insurance arm. The business could be worth more than 2 billion euros ($2.15 billion) in a transaction, a fifth source added.

Achmea is working with bankers at JPMorgan JPM.N to gauge interest in the business, which manages more than 40 billion euros in assets largely from legacy insurance policies that are no longer sold to new customers, the four people said, speaking on condition of anonymity.

Discussions are still at an early stage, and there is no certainty that a transaction will materialise, the sources also said.

Achmea, Athora, JPMorgan and NN Group declined to comment.

The plans come as European insurance groups carve out non-core operations and legacy insurance portfolios in a bid to free up capital held to support these insurance policies so they can invest the money elsewhere.

Swiss insurer Baloise announced a deal this month to offload part of its life insurance business in Belgium, confirming an earlier Reuters report.

Besides NN Group and Athora, Achmea is also sounding out alternative asset managers with existing insurance platforms such as Canada's Brookfield BN.TO, two of the people said.

Brookfield declined to comment.

NN Group and Athora are seen as having a competitive advantage over other prospective bidders as they already operate in the Netherlands, one of the four sources said.

Achmea is considering different deal structures, such as an outright sale or a joint venture with a partner, another of the sources said.

For NN Group, whose roots go back nearly two centuries, a deal with Achmea's life arm would be one of its biggest acquisitions in recent years.

In 2022, the Amsterdam-listed group acquired the life insurance activities of ABN AMRO Verzekeringen.

NN Group and Athora previously teamed up to acquire Dutch insurer VIVAT in 2020, with NN Group taking the target's non-life operations and Athora the life insurance business.

Athora is an example of the growing number of insurance companies backed by alternative asset managers which see in life insurance a source of long-term capital to invest.

The flow of private capital into the sector has raised the attention of regulators and bodies like the International Monetary Fund.

The heightened scrutiny of the sector comes in the wake of the collapse of Italian insurer Eurovita, which Cinven had acquired in 2017.

($1 = 0.9314 euros)

(Reporting by Pablo Mayo Cerqueiro, Amy-Jo Crowley and Andres Gonzalez in London; Additional reporting by Bart H. Meijer in Amsterdam; Editing by Anousha Sakoui and Jane Merriman)

((pablo.mayocerqueiro@thomsonreuters.com))