Labour are under investigation after they were found charging white people more to attend a conference than those from an ethnic minority background.
Jeremy Corbyn is due to deliver a speech at the event in Loughborough on 17 February. As part of a move to increase attendance from the black, Asian, and minority ethnic (BAME) community, white party members are being charged £40 a ticket compared to £30 for non-white members.
Tory MPs have now accused of the party of discrimination and have asked the Equality and Human Rights Commission to see if any rules have been broken.
Andrew Bridgen, the North West Leicestershire Tory MP, said the move shows the party are abandoning working-class white members.
He said: "I believe this is not only discriminatory and illegal it's also extremely divisive – setting communities against each other and opening a Pandora's box for extremists at both ends and Labour must refund their illegal racial surcharge."
Conservative vice-chairman James Cleverly added: "Discriminating against people based on the colour of their skin is totally wrong and Mr Corbyn must end this practice now."
Rebecca Hilsenrath, chief executive of the Equality and Human Rights Commission, confirmed to Bridgen that the organisation was investigating, reports The Times.
She said: "The legal team is considering whether or not to use one of our statutory powers in relation to enforcement of the Equality Act," she said in an email. Leicestershire police had said that the matter was not in their jurisdiction.
A Labour spokesman said: "The basic price of a conference pass is the same for all members but, at the request of our East Midlands Regional Board, the party will subsidise part of the cost of this year's conference pass for BAME members to encourage attendance and improve representation."