Labour is set to hold a special summit on how to help self-employed workers in the wake of Tory plans to hike their National Insurance payments.
Shadow chancellor John McDonnell said Labour "had always been the party of workers, of artisans" and would produce a "radical" plan to deal with the growing number of people who work for themselves in the so-called 'gig economy'.
Next month, he will chair talks with unions, self-employed workers and small business owners as the party seeks to develop its new policy.
He announced the move at a Labour economy conference in Glasgow just days after Philip Hammond used his Budget to reveal a planned 2 per cent rise in Class 4 National Insurance Contributions (NICs).
Mr McDonnell recalled that the Labour movement "was born out of the struggle for decent pay and conditions when new technologies were ripping up existing ways of working".
He told the conference: "We need that same spirit and vision again. So I'll be convening a summit next month of unions, the self-employed and small businesses to develop Labour's policy on self-employment.
"We want to win the widest possible support for a radical, Labour vision of how to adapt to a changing world.
"We are the party, we have always been the party, of workers, of artisans, those who set up their own small enterprises and small businesses.
"That is the message we should carry to every part of the community."
In contrast, he said Conservative Government "represents the giant corporations and tax-avoiders and tax-evaders".
He said: "This week's Budget made that only too clear where their priorities lie.
"Labour will make different choices when we return to government."
The Tories are "breaking a clear manifesto promise" not to raise NICs, he said.
But the shadow chancellor added: "When have you ever been able to trust a Tory manifesto?"
The Government's plans "to push a £2 billion tax rise on low and middle-earner self-employed make little sense", he argued, saying: "The justification offered by the Government does not stand up.
"You can't simply demand more taxes off people without offering something in return."
He went on to accuse the Tories of "effectively blaming self-employed people for the dysfunctional labour market that we have" and also hit out Mr Hammond for "boasting about tax cuts to the corporations and the rich".
Mr McDonnell asked: "What's progressive about raising taxes for low-paid drivers, while the Government goes ahead with cuts to capital gains tax for a tiny few?
"What's progressive about raising taxes for low-paid self-employed cleaners, while the wealthiest families in the country get a cut in their inheritance tax?
"What's progressive about raising taxes for plumbers, while multinational corporations see their tax bills slashed year after year?
"What's not fair is £70 billion pounds of tax giveaways for the wealthiest and for corporations is taking place while they're hiking taxes on middle and low earners.
"That's not fair. That's not progressive. And to be frank, it's just not right either."