Image copyright Getty Images Image caption Holyroodhouse is the official royal residence in Scotland

Opening a royal palace in Wales could bring in an extra £36m in tourism spending, a report has said.

The Gorwel think-tank said the case for an official royal residence should be considered, saying it could attract thousands of visitors but be seen as an extravagance.

Royal broadcaster Brian Hoey said a new residence would be a "wonderful idea".

But the Wales Green Party, which opposes the monarchy, said the tourism benefit had been exaggerated.

Unlike the other nations of the UK, there is no official residence for a member of the royal family in Wales.

Gorwel's report examined the case for and against setting up a royal palace in Wales to match those elsewhere.

Doing so would give Wales political and economic benefits, it argued, leading to a long-term increase in tourism numbers and create up to 100 jobs.

The report suggested between £765,000 and £3.6m annually could be generated in tourism income, as well as a further £510,000 - £2.4m in indirect spending with between 55,680 and 266,927 visitors a year.

Image copyright Getty Images Image caption Cardiff's City Hall is suggested as one possible location for an official royal residence

The report was not specific about what kind of building should be used, but said a new site would be "more interesting than a building that had been there for many years already".

It also suggested a number of older buildings could be adapted for use in and around Cardiff, including City Hall and Duffryn Gardens.

But the report's authors, Prof Russell Deacon and Scott Prosser, also list potential drawbacks including that it could be seen as extravagant during a time of austerity.

They said it could also distract or displace tourism for other sites and was "unlikely to be a substantially profitable enterprise".

There would also likely be "significant costs" in renovating an existing building or establishing a new one, while security and anti-terrorism measures "could act as a substantial drain on the public purse".

Image caption Brian Hoey said a royal residence would increase the profile of Wales

Prof Deacon said: "There are a number of royal events coming up, which benefit other capitals, such as London and bring in increased tourism there.

"We'd like to see whether royal occasions could also benefit Cardiff, why is Wales left out of that tourism bonanza? Perhaps we should share some of that as well, we're part of the United Kingdom and in that respect we should have a royal residency here too."

Royal author and broadcaster Brian Hoey said: "If there were to be a royal residence here in Wales, it would increase the profile of Wales not only throughout the United Kingdom, but throughout the world.

"Because we would then be on the same standing as Northern Ireland and Scotland, and other parts of England of course."

There are official royal residences in England - including Buckingham Palace and Windsor Castle - Scotland has the Palace of Holyroodhouse and Northern Ireland has Hillsborough Castle.

The Prince of Wales has a private estate in Llwynywermod in Carmarthenshire, which is often used commercially for holiday lets.

Image caption Grenville Ham says the royals have plenty of homes already

The leader of Green Party Wales, Grenville Ham, said: "We've already got 600 castles in Wales, we've already got mountains that bring people here. I think the tourism benefit is hugely exaggerated.

"I don't think the royal family need another home, they've got plenty. If they want to build something in Wales, they should build social housing."

The Green Party previously called for the Queen to be evicted from Buckingham Palace and offered a council house.