Zack Polanski falsely claimed to be a spokesman for the British Red Cross while raising money for an election campaign, it emerged on Tuesday night.
The Green Party leader is said to have repeatedly made the claim when he was running to be deputy leader of the party in 2022.
Mr Polanski put the claim on his website and two donation pages, according to The Times, which also revealed a number of disputed assertions relating to his work experience.
The British Red Cross last night rejected the claim and the Green Party said the spokesman reference was to Mr Polanski hosting fundraisers for the charity. In 2020, Mr Polanski reportedly said on his personal website that he was working as a spokesman for the Red Cross.
Two years later, he is said to have repeated the claim while crowdfunding £400 for his campaign for Green Party deputy leader, which he won.
He said at the time: 'As a spokesperson for the British Red Cross, I care deeply about ending racialised policing for an end to the phoney war on drugs.'
However the British Red Cross told The Times that Mr Polanski 'has not been a spokesperson'. Meanwhile the Green Party said Mr Polanski had been a host 'for several fundraisers for the British Red Cross' and had been supporting its work.
On Tuesday night Labour accused Mr Polanski of being 'caught in the act again' and called on the Green leader to 'come clean with the public'.
Zack Polanski falsely claimed to be a spokesman for the British Red Cross while raising money for an election campaign, it emerged on Tuesday night (file image)
A party spokesman said: 'It's not the first time the Green Party leader hasn't been straight with the public. This is a matter of trust.
'Voters will rightly wonder whether Lib Dem turned Green Polanski believes anything at all, or whether it's just all for a cheap headline.'
The Green Party and the British Red Cross were approached for comment.
It is understood that the charity's records show that Mr Polanski has supported it, but that he has never been an official spokesman. A British Red Cross spokesman said: 'We support people in crisis every day. We are a neutral and impartial humanitarian organisation and to protect our vital work, we do not take part in party-political activity or campaigns.'
Last night Mr Polanski said on X: 'I've always admired the work of the British Red Cross. From their work to support refugees, to their work supporting people in Gaza and conflict zones around the world.'