Companies that evade tax will not receive public contracts, Nicola Sturgeon has vowed.

In her speech to the Scottish Trades Union Congress in Dundee, Sturgeon pledged to ensure that companies who "engage in unacceptable workplace practices" do not receive public contracts.

Sturgeon said: "We will continue to do everything that we possibly can to ensure that public procurement supports good workplace practices and that companies that engage in unacceptable workplace practices - like blacklisting, exploitative use of zero-hours contracts or tax evasion - do not benefit from public procurement."

The First Minister also said that she would use Holyrood's new powers over employment tribunals to abolish tribunal fees to help gender equality. Sturgeon hopes that abolishing the fees would enable women to take their employer to a tribunal over unequal pay much easier.

She said: "Another important step in breaking down gender barriers is ensuring that where there is discrimination, there is access to justice.

"So, with the transfer of powers over employment tribunals, I can tell you today that an SNP government will abolish fees for employment tribunals, ensuring that employees have an opportunity to have their case heard.

"While many local authorities, to their credit, have taken action to deliver equal pay, some continue to lag behind.

"A re-elected SNP government will look to apply penalties to any council that does not honour their obligation to deliver equal pay."

Nicola Stugeon also outlined that if re-elected as First Minister she would not employ "target-led assessments" by the Scottish Government's new social security agency. From April, 2017 the Scottish Government will be in charge of a range of welfare powers.

Scottish Labour responded to Sturgeon's comments by saying that they "would use the powers to stop the cuts".

Alex Rowley, Scottish Labour's deputy leader and campaign manager said: "At the STUC this week Kezia Dugdale outlined her plans to use the new powers of the Scottish Parliament to stop the cuts to public services.

"Whilst the SNP's tax plans have been branded 'pathetic' by the General Secretary of the STUC, Labour will use the powers to ask the top 1% to pay more, with a 50p top rate of tax for people earning over £150,000 a year to invest in education.

"Labour would also halt the privatisation process of the CalMac ferries and fight to keep them in public hands. By contrast Nicola Sturgeon refused to use the front door of the STUC to avoid protestors.

"We can do things differently in Scotland now. Faced with the choice between using the powers of the Scottish Parliament to invest in our economy or carrying on the cuts Labour would use the powers to stop the cuts."

Scottish Liberal Democrat leader Willie Rennie said that the SNP are "frozen to the spot" and are not offering an alternative to austerity.

Rennie said: "The SNP are frozen to the spot - on income tax, on local tax, on education, the list goes on.

"By refusing to be bold on local taxation and by refusing to use income tax powers to make a transformational investment in education, they are not offering an alternative to austerity.

"They are pretending their hands are tied, preferring to point a finger down the road to Westminster instead of using the new powers coming to Holyrood they've spent decades campaigning for."

The Scottish Conservatives dismissed Sturgeon's speech as "spin and sound bites".

The party's welfare spokesman John Lamont said: "This is just more spin and sound bites from the SNP.

"The UK Government has made good progress in getting people back to work and out of poverty. Our policies have helped the economy grow which has created more jobs.

"It is a shame the Nationalists do not want to work with us on lifting people out of poverty in Scotland."

The Scottish Greens have been approached for comment.

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