Co-leader of the Green Party Jonathan Bartley has announced he will step down from the role at the end of July.

Mr Bartley, the party's longest serving leader, said he is "hugely proud" of what the Green have achieved in the last few years and that he hopes to play a "full, if different role" after standing aside.

Fellow co-leader Sian Berry will continue as acting leader of the party while a leadership election takes place.

Mr Bartley said the Greens have become a "major electoral force, vying to be the country's third party" under his leadership since 2016.

"I have always believed that leadership is about empowering and encouraging others and this is something I've done throughout my time as co-leader," he said in statement on Monday.

"I now feel that the time is right to step down so that new leaders can be elected.

"It has been an immense privilege to have been the longest-serving leader the party has had - first with Caroline Lucas for two years and then with Sian Berry for three, with Amelia Womack completing the leadership team throughout.

"During this time so many talented people have emerged.

"It's also increasingly clear that we may have an earlier-than-expected general election and a new leadership team needs time to get used to the role, which makes it the right time to step down now and allow the party to choose new leaders."

Mr Bartley has led the Greens alongside Ms Berry since 2018 and served as co-leader for two years with Green Party MP Caroline Lucas before that.

Responding to the news, co-leader Ms Berry said: "Jonathan has been a tremendous colleague. Hard-working, thoughtful, kind, collegiate and full of insight and ideas.

"Every member should applaud the huge part he has played in the Green Party's progress over the past five years.

"His departure leaves many impressive pairs of shoes to fill."

Mr Bartley, who also co-leads the Green Group of councillors in Lambeth, south London, was arrested while taking part in a climate change protest on Whitehall in 2019.