UPDATE 2-Insurer Aflac posts higher first-quarter profit

* Aflac Q1 EPS of $1.22

* Shares unchanged after market close (Adds CEO comments, details on gains)

NEW YORK, April 29 (Reuters) - Aflac Inc (AFL.N), the world's largest seller of supplemental disability insurance, said on Wednesday that net income rose 20 percent in the first quarter, helped by growth at its Japanese unit and the stronger Japanese yen.

Aflac said net earnings were $569 million, or $1.22 a share, compared with $474 million, or 98 cents a share, in the year earlier quarter.

"The weakened economies in Japan and the United States continued to pose challenges for the sale of our products," said Chief Executive Daniel Amos in a statement.

Aflac counts on the U.S. and Japanese markets for the bulk of its business.

The company expects 2009 sales in both countries to be between flat and 5 percent higher, he added, warning that "further economic weakness would likely result in a need to revisit those targets."

The insurer said it had investment losses in the first quarter from complex debt obligations, as well as, Ford Motor Co (F.N) and Security Benefit Life SECBN.UL bonds, among other securities.

Net realized investment losses were $6 million for the quarter, as realized after-tax investment gains mostly offset the after-tax investment losses.

Analysts on average had expected earnings of $1.16 a share, according to Reuters Estimates. It could not immediately be determined if this compared with the company's $1.22 figure.

Columbus, Georgia-based Aflac said total revenue in the first quarter was 12.9 percent higher at $4.8 billion.

Aflac shares were unchanged in extended trading, after closing up 5.62 percent at $29.13 on the New York Stock Exchange. The shares have fallen 36 percent since the start of the year. (Reporting by Lilla Zuill and Elinor Comlay; Editing by Richard Chang, Leslie Gevirtz)