Under ambitious plans to tackle climate change, the EU will require airlines to gradually increase the amount of so-called sustainable aviation fuel (SAF) they use to power planes.

But airlines complain SAF is not widely available and too expensive, hampering competitiveness.

"We don't have enough SAF, and the SAF that we have is very expensive," Luis Gallego, CEO of the IAG airline group bringing together Iberia, British Airways and other carriers, told a press conference.

Gallego was speaking on behalf of Airlines for Europe (A4E), an industry group representing 17 airlines including Lufthansa and Air France-KLM, at an event it held in Brussels.

EU rules require carriers to include two percent of SAF in their fuel mix starting this year, rising to six percent in 2030 before soaring to 70 percent from 2050.

But a study published by A4E estimates SAF production would be 30 percent below levels necessary to achieve the goal in 2030, according to Gallego.

"It is now clear that SAF supply will not be sufficient to meet the six percent target by 2030," said Ryanair CEO Michael O'Leary.

"Unless action is taken now, the only realistic solution is to move the 2030" target, added Gallego.

But the European Commission said the targets were not up for review and the bloc would "stick to" them.

"We consider the current SAF targets to be realistic and feasible," a commission spokeswoman said.

"The focus is now on their implementation, and we will offer support where needed," she added, noting an investment plan for sustainable transport would be presented later this year.

Contributing to almost three percent of carbon dioxide emissions globally, the aviation sector is among the toughest to decarbonise.

SAF -- a biofuel that produces lower carbon emissions than traditional jet fuel, made from plant and animal materials like cooking oil and fat -- is seen as a crucial ingredient to hitting emissions targets.

It is expected to provide 65 percent of aviation's "net zero" mitigation by 2050.

tq/ub/ec/sbk

IAG - INTERNATIONAL CONSOLIDATED AIRLINES GROUP

Lufthansa

RYANAIR HOLDINGS PLC

Air France-KLM

Airbus Group