The Green Party has reversed its historical opposition at HS2, with members backing the change of position at their party conference.

A motion which won the backing of a majority of Greens at the Manchester conference means the party is now officially supportive of building the high speed rail project in full.

This includes two northern legs scrapped by the Tories, stretching from Birmingham to Leeds and to Manchester, where the party wants to see a proposed underground train station terminus built.

The move could put pressure on Sir Keir Starmer’s Government to consider reviving northern portions of HS2 in order to prevent the Greens from wooing Labour voters.

The Green Party came second in 40 constituencies at the election, all but one of which were to Labour, suggesting the path to future success could lie in picking a fight with Sir Keir’s party.

Carla Denyer, the Green co-leader who could not make a speech at the conference after developing Covid-like symptoms, welcomed the motion.

She said: “The Green Party has long supported the principle of a new north-south high speed rail line but had serious concerns about the specific route of HS2 and the environmental impacts of this route.

“However, this first phase of HS2 between London and Birmingham is well under way and most of the environmental impacts of construction are already baked in. So this is a pragmatic decision by the Green Party. It moves us on.”

She added the northern leg of the project was “always the most important in terms of tackling capacity issues on our railways”.

The Greens’ other co-leader Adrian Ramsay had signalled he was supportive of the change in policy ahead of the vote, which took place on the final day of the party conference.

He told the PA news agency there was “a case” for building HS2 in full, but said official policy was a matter for party members.

In the past, the Greens have been critical of the environmental damage caused by the London to Birmingham section of HS2, and opposed building the project when it began.