Members of the Senedd who lie could lose their seats under new recommendations being made to the Welsh government.

But the Senedd’s Standards of Conduct Committee has stopped short of recommending that deliberate deception be made a new criminal offence – to be investigated by the police and prosecuted in the courts.

The committee said the existing standards regime should be strengthened, with the ultimate sanction of a referendum-style vote in an MS’s constituency to decide whether they stay in office.

Under the plans the Senedd’s standards commissioner would also have the power to start their own investigation, rather than wait for a complaint, and could compel an MS to issue a correction.

If they do not make that correction then they would be considered to have broken the rules, or code of conduct, and face tougher sanctions.

The report also calls for an existing law restricting untruthful statements by candidates for election to be strengthened, and for lay members, from outside the Senedd, to join the standards committee.

This has been the case in the House of Commons’ equivalent committee since 2015, using people from outside the institution with relevant knowledge to bring an “independent and external perspective” to decision-making.

If the Welsh government accepts the plans then MSs would be subject to a beefed-up code of conduct with a rule to act “truthfully” replaced with an explicit instruction to refrain from making deliberately inaccurate statements.

Ministers are currently considering a previous committee report which recommended the Senedd introduce a “recall” procedure which would give voters the chance to remove MS’s who had misbehaved.

In their latest report the committee concluded that introducing a criminal offence risked unintended consequences which might outweigh any benefits.

It had heard evidence that it might overwhelm police and the criminal justice system – which is already facing severe backlogs – and that any allegations of deliberate deception would have to reach the criminal standard.

The committee also wanted one standards system, and not have lying treated separately and seen as more serious than other breaches.

If the circumstances were deemed serious enough – subject to a recommendation from the committee and a vote in the Senedd – committee members felt that the ultimate decision should lie with the electorate to recall their Senedd member.

Under the plans the disciplinary procedure would remain unchanged.

The standards commissioner would investigate, the committee would consider the report and recommend a sanction before the Senedd would vote on it.

Any MS falling foul of the new rules would have a note about the case on their biography on the Senedd website.

The committee also called on the Welsh government to clearly define deliberate deception.

Hannah Blythyn, the Labour MS who chairs of the Senedd’s standards committee, said: “Toughening rules for Members of the Senedd and candidates standing for election is critical at a time when public trust in our institutions is low.

“By strengthening the law governing elections, toughening our code of conduct and giving more power and independence to those investigating complaints, we can start to rebuild public trust in our political institutions and support a parliament fit for the future.”

Committee members considered three options:

• To create a criminal offence of deception which would end up in the criminal courts
• To use an existing investigative body – the Public Services Ombudsman for Wales has been mentioned and gave evidence to the committee – and to bring in a civil sanction such as a fine
• Strengthen the MS code of conduct and beef up the available sanctions, meaning it would be dealt with through the Senedd’s disciplinary procedures

Four members not on the standards committee, so called “observer members”, also took part in the work.

Three of them – Labour MS Lee Waters, Plaid Cymru’s Adam Price and the Liberal Democrat leader Jane Dodds – favoured an independent process involving a criminal or civil offence.

They supported improvements to the standards system but did not think it would go far enough to meet what the Welsh government had promised the public and the Senedd.

Former counsel general Mick Antoniw, who is now a member of the standards committee, had made a commitment that the Welsh government would legislate in time for the 2026 Senedd election for the disqualification of members and candidates found guilty of deception through an independent judicial process.

He made the concession after the government looked set to lose a vote on the issue, which could have led to the creation of a law that would have made lying a specific criminal offence.

A separate set of rules would apply to candidates standing in a Senedd election.

The committee recommended broadening the UK Representation of the People Act to include deliberate deception, which the Welsh government already has the power to do.

At the moment it is a criminal offence to make a false statement about an opponent’s conduct or character.

A Welsh government spokesperson said: “The Standards of Conduct Committee has produced a detailed and thorough report into deliberate deception as part of its inquiry into member accountability.

“We will now consider its findings and recommendations before responding formally.”

Adam Price, the former Plaid Cymru leader and observer member during the committee’s deliberations, said the “cross-party consensus signified by this report is a globally pioneering step in tackling deliberate political deception”.