Chinatrust Financial, which lost a bid to acquire AIG's  Taiwan life insurance unit, will buy a 30 percent stake of the unit from China Strategic, a source with knowledge of the situation said on Tuesday.

In exchange, China Strategic will take a 9.5 percent stake in Chinatrust via a private placement, the source said, asking not to be identified.

(Reporting by Faith Hung; Editing by Dan Lalor)