The Senedd has called on the UK Government to replace the “outdated” Barnett funding formula with a new needs-based way of setting public spending in Wales.

Rhun ap Iorwerth said having to make a case for fair funding speaks volumes about Wales’ status within an unequal union.

He told the chamber the population-based Barnett formula, which was devised in the late 1970s and only intended as a temporary measure, does not reflect the needs of Wales.

The Plaid Cymru leader described the funding formula as a weak, short-term solution from the 20th century based on the needs of another country.

He said: “It has become more and more apparent over the years that the Barnett formula is well past its sell-by date.”

Calling out apathy at Westminster, Mr Iorwerth accused the Conservatives of placing barriers before any attempts to reform and criticised Labour for refusing to promise change.

Mr Iorwerth told MSs the Barnett formula has been a cornerstone for a broader pattern of unfairness faced by Wales in recent years.

Peredur Owen Griffiths, Plaid Cymru’s shadow minister, said the state of the Welsh budget for the financial year from April shows in stark terms how poorly Wales is served.

He warned: “The experiences of the past few months have conclusively demonstrated that Welsh public finances are on an utterly unsustainable trajectory.”

The South Wales East MS argued the Barnett formula is ill-equipped to address the precarious state of council finances, with the threat of bankruptcy looming large.

Mabon ap Gwynfor focused on the needs of Wales, saying: “The truth is, it's more expensive to provide health and social care to older, more rural and impoverished communities.”

The Dwyfor Meirionnydd MS argued replacing the Barnett formula should be regarded as a vital investment in health.

Rebecca Evans told the chamber it is clear the UK funding model does not work for Wales.

The finance minister said the funding system for devolved governments is characterised by quick fixes, inconsistency, uncertainty and instability.

Ms Evans called for a new relative needs-based approach, overseen by a body independent of the UK Government and to be agreed by all four nations.

She said: “That would be fairer but also more efficient and effective, and it would help reduce the distortions and inefficiencies that arise from the current system.

“It would enable a more rational, transparent allocation of public spending across the UK.”