The Senedd has rejected Plaid Cymru calls to demand HS2 be redesignated as an England-only project to unlock billions of pounds of consequential funding for Wales.

Senedd members voted 42-12 against a Plaid Cymru motion on HS2, a high-speed railway from London to Birmingham, following a debate on 12 March.

The project was classified as a Wales-and-England project in 2015 by David Cameron’s UK Government despite not an inch of track crossing the border.

As a consequence, no funding has come to Wales under the Barnett formula but Scotland and Northern Ireland have received a population share of HS2 spending.

Plaid Cymru has made the case for £4bn in compensation based on estimates of the total cost but the Welsh Government has quoted a £400m figure based on spending to date.

Peredur Owen Griffiths, the party’s shadow transport secretary in the Senedd, warned Welsh rail infrastructure has been systematically underfunded by the UK Government.

Calling for an end to “fundamental injustice”, he said: “Wales has received a fraction of the rail enhancement funding it is owed, our infrastructure has suffered from decades of neglect and the UK Government has failed to deliver the fair funding Wales needs.”

The Plaid Cymru politician pointed to an acknowledgment from Heidi Alexander, the UK transport secretary, that Wales has received low levels of funding historically.

“But this underfunding is not just historical, it is ongoing,” he warned. “Westminster, whether red or blue, continues to deny Wales the consequentials it is due.”

Mr Owen Griffiths raised concerns about reports that UK chancellor Rachel Reeves plans to freeze spending on major new rail projects until after the 2029 general election.

Pointing out that Welsh ministers previously called for £5bn in consequential funding, he told the Senedd: “Clearly, the people of Wales cannot trust this Labour party to stick to its word.”

Mr Owen Griffiths criticised the Welsh Government’s “delete-all” amendment, which was narrowly agreed, for “U-turning” on previous policy positions.

He said: “Now, when it truly matters, they have collective amnesia. What has changed? … The only thing that has changed is Labour’s willingness to stand up for Wales when they finally got the chance to do something about it.”

Peter Fox, the Tories’ shadow transport secretary, accused Labour of playing politics. “It must be embarrassing for Labour backbenchers, hence not many here,” he said.

Labour’s heckler-in-chief Lee Waters pointed out: “There’s nobody on your front bench.”

Mr Fox said: “Politicians in both Wales and England were calling for billions of pounds … but now Labour are in power in Westminster, their call is for just a meagre £400m.”

Labour backbencher Mick Antoniw pointed out that the previous Conservative UK Government could have designated HS2 as an England-only project.

Mr Fox, a former council leader, said the Tory Senedd group has stood against its own party on HS2 funding, adding: “It’s a kick in the teeth that you are turning your back.”

His Conservative colleague Gareth Davies warned of a “grotesque imbalance” between spending on rail in north Wales compared with the south of the country.

Labour’s Hefin David remarked: “The closer we get to an election, the poorer the standard of debate happens to be in this chamber. You would swear … that actually there’s been no progress whatsoever on rail in Wales which is manifestly not the case.”

Dr David pointed out that the newest trains in the whole of Europe now run on the Rhymney line through his Caerphilly constituency following an “incredible transformation”.

Welsh Lib Dem leader Jane Dodds said: “I feel these … debates are really the opposition parties putting down a motion and the Welsh Government saying ‘delete all’, and it feels like on this occasion just for the point of doing it and that depresses me beyond belief.”

Labour’s Alun Davies agreed, saying: “I don’t believe that’s the correct way of approaching these debates. We should look for consensus where possible – and that’s coming from me. We should look towards amending motions rather than deleting them.”

Wales’ transport secretary Ken Skates said the Welsh Government took ownership of the core valley lines and “transformed a liability into an asset”.

He told the Senedd: “And now that we have a Labour UK Government we will transform services across north Wales as well, increasing services by 50% next year.”

Mr Skates said a review of Network Rail processes will ensure Wales finally receives a fair share of all future rail infrastructure investment.