The Welsh Parliament has narrowly rejected calls to establish an independent Wales-specific public inquiry into the Covid-19 pandemic.

With the vote tied at 27-27, Ceredigion MS Elin Jones – the speaker or Llywydd – used her casting vote against the motion in line with convention and Senedd rules.

Conservative and Lib Dem MSs backed Plaid Cymru’s call for a Wales judge-led inquiry but Welsh ministers and Labour backbenchers voted against.

Labour MSs were whipped to vote in line with the Welsh Government, rather than given a free vote, but the party’s group is understood to be united on the issue.

Mick Antoniw said the UK Covid-19 inquiry, which will hold hearings in Cardiff for 10 days from February 27, is as much for Wales as England or any of the four nations.

Mr Antoniw, who is counsel general, the Welsh Government’s chief legal adviser, argued participating in a UK inquiry is the most effective way of ensuring full and proper scrutiny.

Leading the debate on 21 February, Mabon ap Gwynfor told the chamber the UK inquiry’s scope is insufficient to cover every element of how the pandemic was handled in Wales.

“Only a full inquiry for Wales can achieve this,” said the shadow health minister. “And it is a democratic and moral imperative that the Welsh Government heeds the call.”

Mr Gwynfor said Heather Hallett, who chairs the UK inquiry, acknowledged from the outset it will never be able analyse every issue in full.

He pointed out only one afternoon has so far been devoted to Welsh Government testimony.

The Plaid Cymru MS said the Scottish Government has recognised the potential for the UK inquiry to overlook devolved matters by establishing an inquiry.

He urged the Welsh Government to similarly put the public interest before its own, saying: “This is what proper accountability and responsible governance looks like.”

Mr Gwynfor, who represents Dwyfor Meirionnydd, said the Welsh Government correctly asserted its right to do things differently but major mistakes were made in the pandemic.

He told the Senedd: “It is completely hypocritical to insist on diverging from UK policy to strike a tailored approach to Wales on the one hand, while ducking tailored scrutiny for the consequences of those actions on the other.

“Moreover, it does the cause of devolution a considerable disservice by creating the impression that this Senedd cannot hold itself accountable for the laws passed here.”

Russell George, the Tories’ shadow minister, echoed the Plaid Cymru member’s tributes to the Covid-19 Bereaved Families for Justice Cymru group for its tireless campaigning.

He agreed that refusing a Wales-specific Covid inquiry ultimately undermines devolution, accusing Welsh ministers of dodging scrutiny.

Mr George said the answers bereaved families and the people of Wales deserve are best achieved through an independent Welsh judge-led public inquiry.

Adam Price told MSs that the Senedd Covid-19 committee, of which he is a member, will remain a poor substitute, saying: “We’ve been given a task without the tools to fulfil it.”

He said the committee, which was set up to identify gaps in the UK-wide inquiry, risks inadvertently devaluing parliamentary scrutiny and ultimately lacks public confidence.

The former Plaid Cymru leader told MSs: “That would be a disaster for the reputation of this institution and it would be an incredible disservice to the people we are meant to represent.”

Given the impasse, Mr Price suggested establishing a parliamentary commission that would go beyond the narrow terms and limitations of the Senedd committee.

Altaf Hussain, a fellow member of the Senedd Covid-19 committee, similarly broke ranks.

“You would expect me to defend our committee but I cannot,” said the Conservative, who described it as a sticking-plaster solution.

Mr Hussain, a former consultant orthopaedic surgeon, warned the committee can in no way replace a dedicated inquiry and its task of identifying gaps is a near-impossible feat.

“We don't have access to the vast amount of information provided to core participants of the Covid inquiry,” he said. “We can't subpoena witnesses – we can't even demand that the first minister or the former health minister comes before us to explain their actions.”

Heledd Fychan, the Plaid Cymru MS for South Wales Central, described refusal to establish an inquiry as a dereliction of duty, saying: “We should never be afraid of scrutiny.

“We should never be afraid to admit when we get things wrong – it is inevitable…. Avoiding scrutiny is irresponsible. We need to learn lessons and apply them.”

Her colleague Delyth Jewell lost a loved one who was living in a care home during Covid.

She said: “So many people died alone and the sense prevails that the uncomfortable truths about their deaths were swept under some carpet. For the bereaved families, it is a nightmare from which they've never awoken because of those unanswered questions.”

Responding for the Welsh Government, Mr Antoniw said a UK inquiry has the capacity, powers and force to oversee the interconnected nature of decision-making.

Pressed about the Scottish inquiry, he told MSs that he remains unconvinced that it will add anything significantly beyond the UK inquiry.

Mr Antoniw said the Plaid Cymru motion prematurely assumes the UK inquiry will not be good enough before a single hearing has been held in module 2B.

He said: “I believe we must avoid premature assumptions and we must allow both the inquiry and the committee to complete their work in due course.”