Jackie Ballie has accused the SNP candidate standing in the crunch Rutherglen and Hamilton West by-election of “increasingly desperate and dishonest attacks” after Labour was criticised for rolling back pledges on workers’ rights.

Labour said it will ban zero-hours contracts, end qualifying periods for rights and tackle bogus self-employment if it forms the next government at Westminster.

But last month, the party’s policy forum altered the wording of pledges on workers’ rights to suggest there could be flexibility.

The party had wanted to create a single “worker” status for all but the genuinely self-employed, ensuring the same rights.

But Labour’s policy forum agreed to consult on this policy after entering government to create “a simpler framework” that will differentiate between workers and the genuinely self-employed that would “properly capture the breadth of employment relationships in the UK”.

Read more: Angela Rayner forced to deny Labour climbdown on workers' rights

The plans were also changed for “day one” workers’ rights such as sick pay and parental leave that stated this would not prevent “probationary periods with fair and transparent rules and processes”.

Katy Loudon, the SNP candidate vying for the seat, has challenged her Labour opponent Michael Shanks to stand up for Scotland’s workers by calling for his Westminster boss, Sir Keir Starmer, to devolve employment powers to Holyrood.

The appeal comes after figures revealed that 109,000 people in Scotland are currently employed on “exploitative” zero-hour contracts.

But UK Labour's deputy leader, Angela Rayner, has insisted that devolving employment law would be unnecessary if Sir Keir Starmer was to become the next prime minister.

Read more: Angela Rayner rules out devolving employment law to Holyrood

Ms Loudon, currently a local councillor, has said that devolving employment laws to Scotland would allow the SNP Government to ensure that “draconian zero-hour contracts” are banned - a pledge already made by Labour.

She said: “If Michael Shanks is serious about standing up for the people and workers in Rutherglen and Hamilton West then he will demand that his Westminster boss devolve employment powers to Scotland.

"With employment laws at Holyrood, rather than Westminster, the SNP Scottish Government can do the right thing by banning draconian zero-hour contracts and ensuring employment protection rights apply equally to all - something that both successive Labour and Conservative governments have failed to do.”

She added: “The pro-Brexit Labour party have said they will ban zero-hour contracts - but they have also already watered down their pledge to strengthen workers rights, as well as u-turned on pledges to scrap tuition fees, abolish the two-child cap and rape clause, and bring in free school meals.

“Keir Starmer is a politician that bends in the wind with his pledges not worth the paper they’re written on - and his man in Rutherglen is no better, having flip-flopped on Brexit and failed to stand up to his Westminster boss on the Tory austerity policies his Labour party now back.”

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But in response, Ms Baillie, Scottish Labour’s deputy leader, called on Ms Louden to be honest about her party’s record in government.

Ms Baillie said: “Katy Loudon is resorting to increasingly desperate and dishonest attacks on Labour because she can’t stand on the SNP’s record.

“When Labour introduced the National Minimum Wage, the SNP didn't bother to show up; and while the last Labour government lifted two million pensioners and children out of poverty, this SNP government has let 40,000 more children fall into poverty in the last decade.”

She added: “Within the first 100 days of government, Labour will introduce our transformative new deal for working people which will strengthen workers’ rights across the UK - banning exploitative zero-hour contracts, extending sick pay and ensuring the minimum wage is enough to live off.

“Instead of doing the Tories’ work for them by attacking Labour, Katy Loudon should show she is willing to stand up to her own party and break her deafening silence on the SNP’s misuse of public money and their disastrous plans to hike council tax.”