The Scottish Green manifesto will propose removing the “pomp and pageantry” of the monarchy, co-leader Patrick Harvie has said.

Speaking ahead of the party’s campaign launch in Edinburgh on Thursday, Mr Harvie has said his party will set out plans for a written constitution and a republic which can elect and remove heads of states.

The manifesto plans are set to propose the abolition of “unelected heads of state” and a “permanent written constitution” in an independent Scotland.

He said: “The monarchy is a badly outdated and fundamentally undemocratic institution. It represents a different era and feels increasingly irrelevant and ridiculous in the 21st century.

“Yet in a matter of weeks the full pomp and pageantry of monarchy will be on display when the King does the state opening of a new government.

“We should be able to challenge power and elect or remove our head of state through the ballot box, like most countries do.”

He went on to demand a written constitution which would be used to “avoid the kind of power grabs and stunts we have seen from Westminster”.

“The Scottish Greens are the only party that is calling for an independent Scottish republic where power lies with the people rather than being banded down like a family heirloom.”