The leader of one of the country's biggest trade unions has hit back at Labour after being told his vote on the party leadership election had been blocked.
Mark Serwotka, general secretary of the Public and Commercial Services (PCS) union, said it was "extraordinary" to be told he did not share Labour's values.
He registered to vote through his membership of another union, the GMB, and backed Jeremy Corbyn, only to be told by email that it would not count.
He told the Press Association he had voted precisely because he shared the "aims and values" of Mr Corbyn - a phrase Labour is using to ban thousands of people from taking part in the election.
Mr Serwotka said he had not been a member of any political party for 20 years, but decided to take part in the Labour leadership election because he agreed with Mr Corbyn's policies.
"It is extraordinary to be told you cannot vote because you don't share Labour's values, when no-one (from the party) has spoken to me.
"I voted precisely because I share the aims and values of Jeremy Corbyn on anti-austerity, equality, a fair society and strong trade unions.
"Those are the messages I wanted to positively vote for. I have thought for some time we need a new approach to politics in Britain rather than the same old, same old, and that is what Jeremy Corbyn is offering."
Mr Serwotka said he hoped people would not be deflected from any attempt to destabilise the Labour leadership election process, and if anything, should be more determined to vote.
The PCS, which represents civil servants, is not affiliated to Labour and a party spokesman would not be drawn on Mr Serwotka's case, but said it was barring anyone who does not share its values and aims amid concerns about "infiltrators" in the contest.
Acting leader Harriet Harman has insisted there will be no doubt about the "integrity" of the Labour leadership contest following news that less than 1% of new supporters - around 3,100 people - have been blocked as infiltrators.