Singapore Airlines Ltd (SIA) on Thursday reported a nearly 9 percent drop in its operating profit for the year ended March, as weakness in its main passenger travel operation offset a stronger cargo business.

Profit reached S$623 million (US$447.65 million) for the financial year, S$58 million lower than a year ago.

The carrier, a barometer of the health of Asia's competitive airline industry, has come under pressure due to weakening demand for full-service long-haul travel amid competition from low-cost carriers and Middle Eastern network carriers.

"Intense competition arising from excess capacity in major markets, alongside geopolitical and economic uncertainty, continue to exert pressure on yields," the company said in a statement.

Its annual net profit more than halved from year-ago levels to S$360 million.

Operating profit for the parent airline company fell about 20 percent to S$386 million.

But SIA Cargo swung to an operating profit of S$3 million for the year, from a S$50 million loss last year, reflecting a broader improvement in the global air freight market.

Data from the International Air Transport Association shows global freight volumes rose by nearly 11 percent year-on-year over the first three months of the current calendar year.

Singapore Airlines declared a final dividend of 11 cents per share for the 2016/17 financial year.