The green group pointed out that the government’s own climate advisers had warned the aviation industry must not rely on biofuels to offset an increase in emissions in the years to come.
“Biofuels are not the magic solution to the climate emergency,” said Mike Childs, Friends of the Earth’s head of policy.
“The international dash to expand the use of bioenergy and biofuels has had significant impacts: displacing food production, harming biodiversity and seizing indigenous peoples’ land.
“If ministers really want to address aviation’s contribution to the climate crisis they must take steps to cut flights – particularly for frequent flyers – and abandon plans to expand Heathrow and other airports.”
The row blew up after Ms Leadsom hailed a “head-start” by Airbus in what she dubbed “a new decade of decarbonisation”.
“Last month, they celebrated the first flight of one of their ‘Beluga’ Super Transporters with sustainable aviation fuel,” she told an event in London.
“An aircraft over 50-feet high and nearly 200-feet long being powered – in part – by recycled cooking oil!
“In 2018, sustainable fuels covered just 0.1 per cent of the industry’s needs. So there’s a massive opportunity to grow this – greening existing power sources as we develop new ones.”
In a tweet on the Airbus move, Ms Leadsom added: “UK will do everything possible to tackle global climate change.”
The controversy comes after ministers admitted they would not decide how to fund a strategy to end the UK’s contribution to climate change until the end of the year.
It means the plans – which will require huge and potentially unpopular changes to transport, energy and agriculture – will only emerge more than a year after the legal commitment was made.
The government had already been fiercely criticised for lacking urgency and practical solutions for tackling the climate emergency in announcements so far.
The climate crisis was barely mentioned by Boris Johnson during the election campaign and he boycotted the Channel 4 debate on the issue – when he was replaced by a melting ice sculpture.
The prime minister is under pressure to step up action after a poll for The Independent found overwhelming support for ending net carbon emissions by the end of this decade.
The 2050 commitment is described as “net zero” because air travel and farming are viewed as unavoidable, but carbon from those activities would be taken out of the air by growing trees or burying carbon dioxide.