Anti-racism campaigners are to protest at the English National Ballet after a dancer admitted being a member of the British National Party.
Clarke has been principal dancer at the ENB since 2003
Principal dancer Simone Clarke was revealed to be a member of the party by the Guardian newspaper last month.
She has since defended her beliefs, and says the BNP is "the only party to take a stand" on issues like immigration.
Campaign group Unite Against Fascism (UAF) is calling for the 36-year-old ballerina to be sacked.
It is planning to protest outside a performance of Giselle, in which Clarke takes the lead role, at the London Coliseum later this week.
The English National Ballet says it will not comment on the political affiliations or personal lives of its dancers.
Calls for Clarke's dismissal have increased since she gave an interview defending her political views to the Mail on Sunday.
"I have been labelled a racist and a fascist," she said, "because I have a view on immigration - and I mean mass immigration - but isn't that something that a lot of people worry about?
"It's not about removing foreigners. It's about border controls," she added.
"I don't regret anything. I will stay a member."
"We would like to see Simone Clarke removed," said UAF spokesman Weyman Bennett. "We believe she had used her position to support a party which fosters division."
He added that such views were "incompatible with a leading arts institution such as the English National Ballet".
The BNP currently holds more than 50 council seats in the UK.
On its website, it portrays itself as the only party "prepared to defend our traditional principles against the politically correct agenda" of Tony Blair and David Cameron.