The flag carrier said in a statement that net profit in the three months ended December was Sg$50.1 million ($39.41 million), down from Sg$142.5 million in the same quarter the year before.

It said the figure was dragged down by a Sg$78 million dollar settlement in a class action suit filed in the US against its freight arm SIA Cargo.

SIA Cargo in December agreed to the settlement with plaintiffs without admitting to any wrongdoing or liability.

The class action was taken against the Singaporean carrier as well as other airlines in 2006 following investigations into price-fixing in air cargo services in the US.

SIA said it also lost Sg$46 million due to diminished value of its assets and its share of losses in associated companies, mainly budget carrier Tiger Airways.

Without the one-off losses, net profit would have risen by 23.1 percent, it said.

"The outlook for the air transportation industry continues to be challenging with airlines offering aggressive fares amidst increasing capacity and fuel prices remaining high by historical standards," SIA said.