The Unite union is planning to hold protests against the role employment agencies allegedly played in "shameful" work practices at retail giant Sports Direct.
Unite regional officer Luke Primarolo said workers employed through employment agencies were being subject to "daylight robbery".
The march will take place in Chesterfield.
Labour's Shadow Secretary of state for Business, Innovation and Skills, has said that Sports Direct's failure to pay minimum wage was 'shameful' and that there are 'systemic failings' in how the company handles employees.
Angela Eagle, who is also Labour's Shadow First Secretary of State, said:
It is shameful that such a large company has been exploiting workers by not paying them the minimum wage.
HMRC must investigate thoroughly and Sports Direct must compensate workers where they are found to have underpaid them.
It is also clear that there needs to be a major change in the culture and working practices at Sports Direct.
Mike Ashley’s admission that he cannot be responsible for everything that goes on in his company is deeply worrying.
Today’s Select Committee hearing has revealed a number of systematic failings in the employment practices at Sports Direct, and it is now vital that urgent steps are taken to address these.
Union workers accused Mike Ashley of "defending the indefensible" during his evidence to MPs on work conditions and staff contracts at Sports Direct.
Mr Ashley admitted his firm had paid workers below the minimum wage and accepted that claims of mistreatment and poor working conditions showed the retail giant had "outgrown" him.
The Unite union attacked the tycoon on its Twitter account as his appearance at the Business Select Committee came to an end.
Sports Direct boss Mike Ashley's performance in front of MPs has been labelled "extremely concerning" by a significant shareholder, ITV News Business Editor Joel Hills has reported.
The tycoon told MPs things had happened at the retail giant that "shouldn't happen" after conditions were likened to a "labour camp".Read the full story ›
Mike Ashley has confirmed to MPs he tried to buy BHS prior to it entering liquidation and had wanted to combine it with his Sports Direct stores.
"I 100 per cent wanted to buy BHS," he said despite protests from his media adviser not to answer the question at the Business Select Committee.
Mike Ashley has told MPs that the claims of mistreatment and poor working conditions at Sports Direct shows the business has "definitely outgrown me".
"I can only do my best and my best may not be good enough," he said.
Mr Ashley earlier pledged to implement a number of changes to working practices within 90 days.
He promised to write to MPs if the time frame needs to be extended.
"You're pushing against an open door," Mr Ashley said on his willingness to deal with issues at his retail chain.
Mike Ashley has told MPs that HM Revenue and Customs is investigating Sports Direct over its failure to pay a national minimum wage.
ITV News Business Editor Joel Hills tweeted:
Mike Ashley said Sports Direct staff had been "over-quick to pick up the phone" after it was revealed that 110 ambulances were called to its main warehouse in the last three years.
The figure related to call-outs between January 1 2013 and April 19 this year to the Shirebrook warehouse in Derbyshire.
"Let us assume that every single call-out was needed," he said. "How are people getting injured at Sports Direct? You cannot have that number of serious incidents - it is impossible."
Mr Ashley added: "I was told that we were over-quick to pick up the phone for the ambulance service."