American International Group Inc is expected to post a first-quarter loss on Thursday, but the insurer's results will not trigger a new capital injection from the U.S. government, a source familiar with the matter said on Monday.

The loss in the first quarter is likely to be significantly lower than the fourth-quarter loss of $61.7 billion, the source said, adding that there was no new bailout for the insurer.

The source declined to be named because the results haven't been announced yet.

AIG's fourth-quarter loss was the largest quarterly loss in U.S. corporate history.

It was announced in March along with a revised bailout package.

Investment losses, writedowns and restructuring charges were the largest drivers of the insurer's fourth-quarter loss, more than wiping out operating profits posted by its insurance subsidiaries.

It was the insurer's fifth consecutive quarterly loss, bringing the total loss over that period to more than $100 billion.

AIG could not immediately be reached for comment.

(Reporting by Paritosh Bansal; editing by Carol Bishopric)

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