The leaders of the Scottish Greens have said it is their party’s job to “inject radical ideas” into UK politics.

At the launch of their campaign for the December 12 General Election, Lorna Slater and Patrick Harvie said the party has been effective in pushing more progressive policies, such as the Living Wage and the four-day working week, into the political fore.

At the launch in South Queensferry, the party unveiled some of the candidates who will be standing in more than 20 seats across Scotland.

Ms Slater told the PA news agency: “The role of the Green Party is the one that we regularly play, which is to keep pushing other parties to be more radical.

“The other parties are committed to endless oil and gas extraction, they’re committed to widening roads, they’re committed to things that are completely the opposite of what is needed to combat the climate emergency.

“Something that we’ve found over and over again in UK politics is that ideas the Green Party introduces to the political lexicon are then taken up by other parties down the road.

“The four-day working week, that’s a Green Party policy that the Labour Party is now talking about.

“Maggie Chapman, who was one of our councillors, was the first politician in Scotland to mention the Living Wage, now everybody talks about it.

“It’s the Green Party’s role to inject these radical ideas into the discourse, and that’s how we effect change.”

Mr Harvie said his party must have “bold, Green voices, demanding that the other political parties rise” to the challenge of halting climate change.

He said: “There’s a real sense of contradiction between what the other parties are saying and what they’re doing when they get a whiff of power.

“Greens need to be there in every Parliament and every part of our country challenging that.”

When asked about the possibility of a coalition in this election, Mr Harvie said he “wouldn’t rule that out for the future”, looking particularly at the 2021 election in Holyrood.

He said: “I think people know that the fairer voting system (at Holyrood) means that they have a big opportunity to put a big, solid group of Greens into Parliament and who knows what the options will be in the future.”

The party pledged to put the issue of climate change at the heart of their campaign in Scotland ahead of December 12, with Ms Slater saying the Greens will “demand climate action”.

Ms Slater, who will not stand for a seat in the election, said: “We have only 10 years to make substantial changes to our society and way of life to stop climate change from becoming a runaway effect which will essentially wipe out 95% of life.

“This is urgent. It’s an emergency, and we expect other political parties to treat is as an emergency.”