LONDON (Bloomberg) — Aviva Plc, Britain’s largest insurer, received regulatory approval for its $3.1 billion acquisition of AmerUs Group Co., as it seeks to harness sales growth in the world’s biggest retirement market.The value of the takeover is $200 million more than the $2.9 billion Aviva said it would pay for the Des Moines, Iowa-based seller of life insurance and annuities when it announced the deal on July 13. The price per share is unchanged at $69 while the total is based on 44.9 million AmerUs shares in circulation today compared with 42.7 million in July.

The deal was completed ahead of schedule, Aviva international executive director Philip Scott said in an interview today. “We hoped to complete by the end of the year so we very pleased to have it all done by today,” he added.

Integration of the company with the British insurer’s existing US operation in Boston will “mean some job reductions where there is overlap”, said Scott, 51. Job cuts will be “primarily” at the Boston unit, he added.

Aviva has said that it expects the takeover to generate annual pretax cost savings of $45 million by 2008 and to contribute to operating earnings per share by 2007.

Aviva employs around 400 staff at its Boston unit. As part of the integration plan, which is expected to be completed next year, AmerUs will be rebranded Aviva and the British insurer’s entire US operation will be based in Des Moines.

AmerUs is the third-biggest provider of stockmarket-linked annuities and the No. 1 provider of stockmarket-linked life insurance products. The purchase gives Aviva a “strong platform with good products and good distribution with which to grow rapidly organically,” Scott said yesterday. AmerUs shareholders approved the transaction in October.