Scottish Green co-leader Patrick Harvie has said he is “really sorry” to see his predecessor campaigning for Labour in the General Election.

Robin Harper, who was the first elected Green parliamentarian anywhere in the UK, has been volunteering with shadow Scottish secretary Ian Murray as he bids to hold the Edinburgh South constituency.

Mr Murray tweeted a photograph of “former trailblazing Green” Mr Harper in his office, saying it was “lovely to have a new volunteer”.

He added: “Welcome aboard Team Murray, Robin.”

It comes after Mr Harper last year quit the Scottish Greens, the party he was co-convener of between 2004 and 2008.

Mr Harvie said: “It’s obviously disappointing when somebody moves away from what used to be their core values, and the core values that are still those of the Scottish Green Party.

“The Labour Party at the moment has gutted their green investment plan, from £28 billion a year, which would have brought the UK up to comparable levels of state investment as the European Union.

“They have gutted that as they say there isn’t enough money for it, but (Labour leader) Keir Starmer says there is always enough money for nuclear weapons.

“That is a leader and that is a party that doesn’t share core values with the Green movement, and I am really sorry Robin has chosen to move away from that and thinks that that is a reasonable compromise to make.”