Flag carrier Thai Airways posted a huge loss of 21.3 billion baht ($592 million) in 2008 because of high fuel prices and protests that briefly shuttered Bangkok's airports, the company said.
The airline made a profit of 4.4 billion baht in 2007, and last year's plunge was the company's first annual loss in 43 years.
"For the fiscal year 2008 Thai Airways International continues to encounter crises such as the continuing sharp rise of jet fuel price, the global economic slowdown as well as the political unrest in the country," the airline said.
In the statement released late Friday, Thai Airways also blamed foreign exchange losses due to the weakening of the Thai baht.
The national carrier reported a 1.6 percent year-on-year increase in its total revenue to 200.1 billion baht, but its operating expenses were up 10.8 percent to 206.8 billion baht.
The airline also reported foreign exchange losses of 4.5 billion baht.
Thai Airways is currently in talks with the government over a rescue package to help revive the struggling carrier's finances.
Finance Minister Korn Chatikavanij has insisted the airline must submit a detailed recovery plan before it receives taxpayer funds.
Thai Airways officials have previously said that the company lost about 20 billion baht when protesters trying to topple the last government seized and shut down Bangkok's two airports for a week in late November to early December.
The occupation stranded around 350,000 passengers in Thailand and battered the kingdom's vital tourism industry.
In January, Thai Airways said it would ask for a delay in the delivery of six A330 aircraft from European aircraft manufacturer Airbus due to a shortage of cash.