Aviva, Britain's second-biggest insurer, is closing in on the sale of its underperforming US business.

The sale is a key part its drive to strengthen its finances in an uncertain economic climate and revive its share price.

The disposal, expected "reasonably soon," is set to fetch less than the £2.4 billion sterling at which the unit is valued on Aviva's books, but should free up capital, the insurer said today.

Aviva is four months into a reorganisation in which 16 lagging businesses that contribute 18% of operating profit - but tie up over a third of its capital - will be sold.

The revamp was launched in July by chairman John MacFarlane, who took day-to-day charge of Aviva in May after shareholders, irked by a 60% slide in the company's share price over five years, forced out chief executive Andrew Moss.

Capital freed through disposals could be used to strengthen the insurer's reserves against a potential further deterioration in the troubled euro zone. Aviva holds distressed euro zone sovereign debt to generate income for customers in the region, and its exposure has been a worry for investors.

Aviva's US business, bought in 2006 for £2 billion is the biggest asset in a for-sale list that also includes the group's minority stake in Dutch insurer Delta Lloyd. A further eight businesses will probably be sold next year, Aviva said, declining to name them.

The company is on track to appoint a replacement for Moss early next year, MacFarlane said, with non-executive directors interviewing candidates this week. Finance chief Pat Regan is seen as a likely potential successor.

Aviva, which sells home and motor insurance as well as life and savings polices across Europe, said total sales fell 5% to £28.9 billion in the first nine months of the year, reflecting tough conditions in Ireland as well as recession-hit Italy and Spain.

Potential buyers of Aviva's US business include investment managers Guggenheim Partners, Apollo Global Management, and Harbinger Capital Partners