Prudential, the British insurance group, has agreed to purchase the insurance arm of a Thai bank as it moves to grow its business in Asia.

Prudential Life Assurance, the local unit of the UK firm, will pay $585 million for Thanachart Life Assurance, a subsidiary of Thanachart Bank. Under the terms of the deal, Prudential will buy out the insurance arm and establish a 15-year partnership agreement with the Thai company's bancassurance business, which currently records some four million clients across at least 630 branches.

The acquisition is expected to double Prudential Thailand's share of the local market. Thanachart is one of the largest insurance entities in the country, posting a net profit of $39.8 million in the year to 30 June 2012. 

The selling price represents a multiple of 5.8 times the company's book value as at 31 December 2011. The sale is set to be completed by the first quarter of 2013, pending regulatory approvals.

Thanachart Bank is 51 per cent-owned by Thanachart Capital and 49 per cent-owned by Scotiabank.