Britam is the biggest company in the Kenyan life insurance and pension annuity sector with just over a fifth of the market. Its property portfolio includes shopping malls, hospitality, housing, student accommodation and offices.

Executives in the industry say the life insurance business has growth potential due to low penetration rates of under 10 percent of the population.

Britam, and privately-held Plum LLP, which is selling the shares, did not disclose the value of the transaction, but they said 348.5 million shares were under consideration.

Britam's shares were trading at 13.60 shillings, giving a potential value of 4.7 billion shillings for the deal.

Britam has a market capitalisation of 29.89 billion shillings (221.46 million pounds) according to Reuters data.

The transaction will require regulatory approvals, Swiss Re and Britam said.

Swiss Re already has a foothold in Kenya, where it bought a 26.9 percent minority stake in another insurer, Apollo Investments Limited, which also has operations in neighbouring Uganda and Tanzania.

Britam also has operations in Uganda, Rwanda, Tanzania, South Sudan, Mozambique and Malawi.

(This story has been refiled to to add dropped word "in" to headline.)

(Reporting by George Obulutsa; Editing by Duncan Miriri and Louise Heavens)