Taiwan-based credit card issuer Chinatrust Financial has offered $2.4 billion for AIG's Taiwan Nan Shan Life unit, outbidding three rival bidders.

While Primus Financial withdrew from the scene after Chinatrust raised its bid to $2.4 billion (T$80 billion), the other two bidders - Cathay Financial and a Fubon Financial Holding Co-Carlyle Group LP partnership - are still on the race for acquiring the Nan Shan Life unit, reports said.

The two are reported to have bid less than $1.5 billion each for Nan Shan Life.

Chinatrust Financial on Friday said it planned to raise T$44.35 billion ($1.34 billion). Chinatrust said it would sell 2.5 billion common shares at T$17.74 per share via a private placement.

"The purpose of the fund raising is to strengthen our capital and financial structure in order to help operations and business expansion in the long term," it said.