UPDATE 3-NAB eyes wealth mgt growth with $660 mln Aviva buy

* To buy Aviva's Australia businesses for A$825 mln

* Sees annual pretax synergies of A$70 million

* Price looks OK, synergies may be unrealistic - analyst

* NAB shares rise 1.4 pct, beating broader market (Adds Aviva Asia Pacific CEO comments, Aviva shares)

By Denny Thomas

SYDNEY, June 22 (Reuters) - National Australia Bank Ltd (NAB.AX) will pay $660 million for most of British insurer Aviva Plc's (AV.L) Australian businesses to become the country's dominant investment platform provider and insurance underwriter.

NAB, the country's biggest lender, pipped AMP Ltd (AMP.AX) and others to clinch the deal -- its first acquisition under new CEO Cameron Clyne.

NAB, which has identified wealth management, insurance and its advisory business as key growth areas, said on Monday the purchase would dent its Tier-1 capital by about 15 basis points, but forecast A$70 million in annual pretax savings.

NAB shares rose 1.76 percent to A$22.49, while the benchmark share index .AXJO was up 0.48 percent.

"The price they paid looks OK, but I don't think their synergy estimates are realistic," said Chris Halls, analyst with Argo Investments Ltd, which owns A$110 million worth of NAB stock.

Aviva, the world's fifth-biggest insurer, joins a growing list of global companies exiting Australia to focus on their domestic markets in the grip of a global financial crisis.

The company, which suffered sharp share price falls in March on concerns that dividend committments and sliding asset values might force it to raise capital, [ID:nLR64522] said the sale would bolster its solvency reserves by 400 million pounds ($659.3 million).

Aviva's Asia Pacific chief executive Simon Machell said the company was on the lookout for potential acquisitions in Indonesia, Thailand and Vietnam, although demand for investment products looked set to remain subdued across the region.

"I expect that market conditions will remain reasonably tough this year and as we go into next year," he told reporters on a conference call.

The company has not at this stage earmarked the capital that will be freed up by the Australian disposal for any specific purpose, Machell added.

Aviva shares were 1 percent lower at 333.5 pence by 0815 GMT, while the FTSE 100 share index was down 0.75 percent. The company had a capital surplus of 2.5 billion pounds at the end of March, it said in its most recent capital update on April 27.