The new welfare system being created in Scotland risks becoming much harsher than under Conservative rule south of the Border, according to leading lawyers.

The warning came as it emerged benefit claimants would face up to five years in jail for providing false details to the new social security agency.

Under the new draft plans, there is little protection for claimants who inadvertently mislead authorities by providing inaccurate personal data.

Prosecutions would be launched if it is deemed a claimant “ought to have known” that a change in circumstances might mean their claim was affected.

Under current UK law there are protections if it cannot be proved they knew they were deceiving the benefits office. Neither can they be prosecuted if they do not gain from the deceit.

Solicitor advocate Liam Ewing, vice-chairman of Justice Scotland, said the bill should be amended to replicate the UK offences and not make the system more harsh.

“Offences of this kind are seldom appropriate and certainly shouldn’t be directed towards those who may be vulnerable and liable to make mistakes,” he said.

Peter Kelly, director of the Poverty Alliance, said: “The section in the new social security bill on investigations and offences is unduly punitive. The reasons people may mislead ministers about their circumstances are complex and we should focus instead on addressing these reasons rather than imprisoning people.”

Emma Trottier, policy manager for Engender said there was a particular danger women would fall foul of the new laws.

“It’s disappointing to see such an emphasis on offences in the Bill, particularly when such a tiny fraction of social security spending is linked to fraud,” she said.

“Scotland’s social security system should aim to reduce, not exacerbate, women’s inequality.”

The Scottish Parliament is currently scrutinising the Government’s plans to legislate for the use of new powers over benefits devolved under the Smith Agreement.

Currently people who claim benefits must abide by the Social Security Administration Act of 1992, which makes it an offence to make false statements or fail to notify officials of a relevant change in circumstances.

In a briefing for MSPs on the social security committee, the law reform body says what ministers are proposing will criminalise conduct which is careless or negligent, rather than dishonest.

In its briefing, the charity warns: “In the criminal context, the phrase ‘ought to have known’ would allow for the conviction of a claimant who had no actual knowledge that a change in circumstances might affect her benefit.”

The current requirement for authorities to prove someone knowingly or dishonestly withheld information and the requirement to show that they gained materially from any deceit combine to make a “substantial” hurdle for the prosecution, Justice Scotland’s briefing says.

“[This] bill creates offences which do not require criminal intent on the part of the accused. It criminalises behaviour or conduct which is careless or negligent rather than intentionally dishonest. Additionally the safeguard of a requirement for proof that benefits would have been affected is absent. In our view such an approach... and the level of the potential penalties is unduly punitive”

Scottish Labour’s social security spokesman Mark Griffin said the difference in approach might be due to shoddy drafting of the legislation, but claimed it was “astonishing” that Scotland could end up with a much more punitive system than the rest of the UK.

“The potential is there for someone to be criminalised and receive a hefty sentence for making an honest mistake that may not even affect their entitlement,” he said. “This will crate a two-tier system in different parts of the UK. That is not in keeping with promises of a system based on fairness respect and dignity.

“I would expect the Scottish Government to bring forward amendments immediately to give people reassurance - and if they don’t we certainly will.”

A Scottish Government spokesman said: “This Government will not criminalise genuine errors made by social security applicants.

“In all cases, we will take individual circumstances into account, including when we are deciding whether or not to recover any overpayments that arise. This is in line with our determination that people are treated with dignity and respect – something that is sorely missing in the current, discredited DWP system.

“We will be considering further the points made by Justice Scotland.”