French-Dutch aviation giant Air France-KLM on Thursday said its net loss narrowed by more than half last year but would need more capital strengthening measures due to the pandemic.

The airline's losses totaled 3.3 billion euros ($2.9 billion) last year.

It said the capital strengthening measures could amount to some 4 billion euros and acknowledged that the omicron COVID-19 variant had hampered positive trends after a good start to the fourth quarter.

"This new step in the recapitalization plan measures intends to further restore the equity position," it said.

The company said it would not be giving guidance for 2022 due to the uncertainty over the pandemic and over when Japan and China would fully reopen to travel.

"After a good start of the fourth quarter and the reopening of the United States early November, the rise of the omicron variant hampered in December the continuous increase in load factors for the medium-haul and domestic traffic," it said.