MetLife Inc, the largest life insurer in the United States by assets, reported a 37 percent decline in first-quarter net income on Thursday, hurt by investment losses amid the economy's credit crunch.

The New York-based insurer reported net income of $648 million, or 84 cents a share, down from $1.02 billion, or $1.28 a share, a year earlier. Analysts surveyed by Thomson Financial forecast operating profit of $1.48 per share.

During a rough first quarter for stock and bond markets, the insurer's investment portfolio lost $560 million compared to $58 million a year earlier. Losses in the latest quarter included $150 million in credit-related losses, in line with the company's expectations.

Operating earnings, which exclude investment gains and losses and one-time items, rose to $1.52 a share from $1.41.

Revenue grew by 0.9 percent to $13.03 billion as premiums grew 12 percent to $7.59 billion.

The international insurance segments were up 10 percent to $137 million because of growth in Latin America.

Chairman and Chief Executive C. Robert Henrikson said, Despite the challenges posed by the credit and equity markets, we continued to execute well on our plans.

Last month, MetLife approved a second $1 billion stock-repurchase program.

MetLife's shares were up $1.09 or 1.8 percent to $61.94 in after-hours trading.