Plaid Cymru attack Labour's 'inaction' over funding
Plaid Cymru has accused Labour of failing to fight for more public funding for Wales.
It said the former Labour-run Treasury had no plans to change the formula for funding the Welsh Assembly Government, despite evidence it was short-changing Wales.
Labour said Plaid's comments were "reheated revisionist nonsense".
The row comes as campaigning gets underway in earnest for the assembly election on 5 May.
Labour and Plaid have been in coalition in Cardiff Bay since the last election in 2007, but in recent weeks have started attacking each other as they part company to fight the election.
Plaid said Labour failed to convince the Treasury to take action on the way Wales is funded when it was office in Westminster.
Documents released following a freedom of information request show the previous UK government had no plans to reform the so-called Barnett formula before last year's general election.
Critics have long argued the funding formula - which sets the size of the assembly's budget based on Wales' population - does not meet Wales' needs.
Published in July 2009 and commissioned by the Labour-Plaid assembly government, the Holtham report said the formula risked depriving Wales of £8.5bn over a decade.
The coalition assembly government used the findings to press the UK to reform the formula.
But a letter from the Treasury, obtained by Plaid, shows that in March last year the then Labour government "has no plans to change the Barnett formula".
The documents say former Welsh secretary Peter Hain and ex-first minister Rhodri Morgan made representations to the Prime Minister to consider the Holtham Commission's findings.
But Plaid's deputy leader, Helen Mary Jones, the party's candidate in Llanelli, said: "It is appalling to think that so many millions could have been spent on building hospitals, closing the education funding gap or supporting businesses but due to Labour's incompetence and ignorance it has been lost."
Former First Minister Rhodri Morgan responded, saying: "Plaid Cymru, yet again prove they are ideologically driven but statistically challenged.
"What Plaid forget is that in the first assembly the funding coming to the assembly grew by 10% a year in cash terms or 7% in real terms.
"That was well in excess of any previous increase but clearly was going to lead to convergence because that's how the Barnett formula works."
He added that in the second assembly the increases continued at a 6.5% in cash terms or 4% in real terms, while during the third the average annual increase was some 4% in cash terms or 2% in real terms.
Meanwhile on the election trail, Welsh Labour leader Carwyn Jones will lead his party's campaigning in Cardiff South and Penarth on Monday morning, beginning with a news conference, before moving to Carmarthen West and South Pembrokeshire, with a rally in Pembroke Dock in the afternoon.
It follows a weekend which saw the Tories become the first party to officially launch their campaign, with David Cameron on the campaign trail in Wales on Friday.
On Monday, assembly leader of the Welsh Conservatives Nick Bourne and Clwyd West candidate Darren Millar will visit the Royal British Legion Club in Colwyn Bay to publicise a new armed forces card.
The Welsh Liberal Democrats will also launch a mini manifesto for Montgomeryshire, with Wyn Williams and leader Kirsty Williams visiting a Welshpool market.
Plaid Cymru leader Ieuan Wyn Jones, will visit Anglesey golf club to highlight the importance of sports tourism to the Welsh economy.