Campaigners have called on the government to come clean about the extent of royal powers and when they have been used.

The call comes after a damning report in the Guardian newspaper today, in which evidence emerged that Prince Charles put pressure on John Major's government to change new legislation.

The changes were demanded so that tenants of the Duchy of Cornwall would not be granted their right to buy their homes, a right that is given to every other leaseholder in the country.

The changes were made against the government's wishes, because of concerns a row might cause a constitutional crisis.

Graham Smith, speaking for Republic, said today:

"This is an absolute outrage. That we have a man who can threaten a constitutional crisis unless he gets what he wants is disgraceful."

"Buckingham Palace and the government have lied to the country, claiming that Queen’s consent is a "purely formal" part of the parliamentary process and is granted by the monarch as a matter of course."

"They have also claimed that "this process does not change the nature of any such bill". These claims are a lie."

"Prince Charles needs to be called to account for his actions, and the government needs to come clean about the extent of royal interference."

"This is just the latest in a series of revelations about the extent of royal interference. The Queen has lobbied to have herself exempted from environmental laws, race discriminations laws and to hide her personal wealth. This has to stop."

"The royal consent rules need to be scrapped, and we need to know exactly what laws were changed to suit royal interests as a result of royal lobbying."

Read the Guardian report.