LONDON - British life insurer Phoenix posted an above-forecast 48% rise in its 2020 operating profit and raised its cash generation target, it said on Monday, boosted by its purchase last year of Swiss Re's British business ReAssure.

Phoenix has expanded rapidly in recent years. In addition to ReAssure, it bought Standard Life Aberdeen's European and UK insurance business in 2018.

The insurer specialises in books of life insurance business closed to new customers but has also been expanding its open books.

"2020 was a landmark year for Phoenix during which we completed the acquisition of ReAssure and became the UK's largest long-term savings and retirement business," Chief Executive Andy Briggs said in a statement, adding that the insurer was accelerating its open business growth strategy.

Operating profit came it at 1.2 billion pounds ($1.66 billion, compared with a forecast 955 million pounds, according to a company-supplied consensus poll.

Phoenix lifted its 2021-2023 cash generation target by 200 million pounds to 4.4 billion pounds, helped by new business.

Cash generation was a record 1.7 billion pounds in 2020.

Open new business saw record incremental long-term cash generation of 766 million pounds, up 59%.

Assets under administration rose 36% to 338 billion pounds.

Phoenix said it would pay a final dividend of 24.1 pence per share.

($1 = 0.7239 pounds)

(Reporting by Carolyn Cohn; editing by Simon Jessop and Rachel Armstrong) ((carolyn.cohn@thomsonreuters.com; 44 207 513 4391;))