The International Air Transport Association (IATA) said in a statement that production of "sustainable aviation fuels" was expected to reach 1.3 billion litres in 2024, more than double the figure for the previous year.

That was below the 1.9 billion litres IATA had forecast for this year for the fuels, which are produced from sources such as "biomass" -- vegetable or animal matter -- or used cooking oil.

It forecast the level would rise to 2.7 billion litres in 2025 -- just 0.7 percent of the fuel used by aeroplanes worldwide.

"We're not seeing sufficient supply coming into the market," IATA Director General Willie Walsh told AFP.

"That's a criticism of the current, the major traditional fuel suppliers who have not been delivering sustainable fuels and not making the required investment," he added.

"This is frustrating and of great concern to us because I think it's in everybody's interest that we see this transition to net zero" carbon emissions, he said.

Countries are seeking low-carbon energy sources to curb the climate crisis caused by planet-warming emissions.

IATA has set a target of net zero emissions for the sector by 2050, counting heavily on sustainable fuels to meet it.

Walsh called on governments to help boost production of these fuels.

"I don't think (the target) is in danger right now," he said, but added: "If this trend continued beyond 2030, then I would be concerned."