The anti-monarchy group Republic said Thursday that the queen and her family cost British taxpayers five times more than has been revealed.
Republic said it costs taxpayers more than 200 million pounds ($320 million) each year to support Queen Elizabeth II and the rest of her extended family.
That is far more than the official figures released by the palace, which show the royals cost taxpayers just under 40 million pounds per year.
The figures released by the group on Thursday are based on the cost of providing security protection for the extended royal family, the cost of royal visits to other countries and throughout Britain, and the income produced by vast tracts of lands and business enterprises held by the royals.
Graham Smith, a spokesman for Republic, said the British royals receive far more taxpayer support than their counterparts in the Netherlands, Denmark and other countries in Europe that still maintain monarchies.
"There is not enough transparency," he said. "A monarchy can be done a lot cheaper. The next most expensive is in the Netherlands, and the British monarchy is more than twice that costly."
He said presidential systems cost far less to maintain.
Buckingham Palace officials said there would be no response to the Republic claims that the true costs are much higher than the public has been told. They plan to release their own figures in the coming weeks.
The Republic figures include revenue lost to taxpayers by royal ownership of lucrative property enterprises, including the Duchies of Lancaster and Cornwall.
"The key point is that if we got rid of the monarchy those properties would transfer from the Crown to the country and the revenue would go to the Treasury," Smith said.