The Queen's Diamond Jubilee takes place in 2012
A Labour election candidate faces disciplinary action after describing the Queen as a "parasite" and "vermin".
Peter White, who is seeking election to Havering Borough Council in east London, wrote the comments on Tory MP Andrew Rosindell's Facebook page.
Mr White said the Queen "milks this country for everything she can".
A London Labour Party spokesman said he would be "required to explain his comments". Mr White has apologised for his remarks.
Mr White is hoping to win a seat in the council's South Hornchurch ward in May.
Mr Rosindell has called for a public holiday to mark the Queen's Diamond Jubilee in 2012, which prompted Mr White's response.
"What is the point of celebrating the Diamond Jubilee of someone who is born into a position of privilege, she is a parasite and milks this country for everything she can," Mr White wrote.
"She has more front than Margate asking for extra money from the civil list. Maybe she should sell a couple of her properties.
"Maybe if she wants Buckingham Palace to be maintained from public funds she should open it to the public."
He added: "Don't get me wrong, I have no problem with a public holiday but lets (sic) have one that means something, rather than celebrating vermin."
The London Labour Party spokesman said: "Peter White has been summoned to a meeting with key members of the local party and officers from the London Regional Labour Party."
In a statement issued via the party, Mr White said: "The way I expressed myself was totally inappropriate.
"I regret what I said and apologise unreservedly."