Aviva's main brand is Norwich Union

Aviva, which owns Norwich Union, said that if a takeover is agreed, it would be funded through internal resources, external debts and a share issue.

Amerus, based in the Iowa, is valued at about $2.3bn (�1.3bn).

Buying Amerus would enable Aviva to increase its presence in the US, where it has previously admitted that it is under-represented.

'Value creating'

Aviva announced in May that sales grew 26% in the first three months of this year to �7.9bn, with a 21% increase in international sales driving the rise.

"These discussions [with Amerus] are consistent with Aviva's stated strategy of pursuing value creating acquisition opportunities in key growth segments of the major global long term savings markets," said Aviva.

In March Aviva pulled out of talks to buy UK rival Prudential after failing to reach agreement with the Prudential board.

Aviva is the world's sixth largest insurance group, with assets under its management of �317bn.