LONDON (AP) ― Prince Charles will keep his little-known veto over some planned laws, a power that dates back to the Middle Ages, after the British government said Monday it was not going to rewrite ancient constitutional rules.

New evidence that the heir to the throne has been playing an active political role has touched a nerve among anti-monarchists, but Prime Minister David Cameron’s office said it did not plan reforms.

Parliamentary records show that Prince Charles has been consulted over at least 12 different planned laws over the last six years, with his consent sought over proposals on subjects including gambling, road safety, London’s 2012 Olympics and housing.

Concern was raised after The Guardian newspaper published a letter obtained under a freedom of information request showing that Parliamentary officials had reminded a House of Lords member that a proposed law would need consent from the prince.

Since around the mid-1330s, the Prince of Wales ― who was then Edward of Woodstock, also known as the Black Prince ― has been asked to approve legislation that could affect the Duchy of Cornwall, the 55,000-hectare estate established by Edward III to provide income for the heir to the throne.

Cameron’s office said constitutional law dictates that Charles is currently consulted over laws that could potentially have an impact on the duchy, or on his interests in Wales or Chester. Charles is Prince of Wales, Duke of Cornwall and the Earl of Chester.

“If it is something that is specific to the Principality of Wales, the Earldom of Chester or the Duchy of Cornwall, then that consent is required and it’s long been the case,” a spokeswoman for Cameron said, speaking on customary condition of anonymity in line with policy.

Queen Elizabeth II ― who has a ceremonial role in granting approval to every law passed by Parliament ― must also offer consent to legislation that affects her personal property or hereditary revenues, Britain’s cabinet office said.

Neither Cameron’s spokesman nor Prince Charles’ office would say whether the prince had vetoed any planned legislation or demanded alterations.

“This is not about seeking the personal views of the prince but rather it is a long-standing convention in relation to the Duchy of Cornwall, which would have applied equally to his predecessors,” the prince’s office said in a statement.

Opponents said the disclosure threatened to undermine Britain’s democracy and muddied the conventions under which the royal family is expected to refrain from involvement in day-to-day politics.

“That such a loophole exists shows our constitution is fundamentally antidemocratic,” said Graham Smith, spokesman for Republic, which campaigns for the abolition of the monarchy.

Prince Charles has been known to publicly air his views on environmental issues, warning in 2008 of what he claimed were the dangers of genetically modified crops. He also successfully lobbied developers to switch their plans for a glass-and-steel tower on the site of a former London army barracks to a more conservative architectural style.

Last week, Britain won agreement from 15 other Commonwealth nations where the queen is head of state to modernize ancient royal succession laws. It means princesses will now have the same right to the British crown as their male siblings.

But Cameron’s spokeswoman said reforms wouldn’t extend to changing the process for consultations over proposed laws.

“I know of no plans at the moment to look into it,” she said.