Liam Fox has called on Chancellor George Osborne to ease the tax burden on business in next month's Budget.
The former defence secretary also wants changes to the labour market to make it easier to hire and fire employees.
The Tory MP argued in the Financial Times for further public spending cuts to fund employment tax reductions.
It is Mr Fox's first major political intervention since he resigned from the cabinet four months ago over his links to his friend, lobbyist Adam Werritty.
His call comes as business group the CBI has separately urged the government to give a £500m boost to business in the 21 March Budget, through a series of "targeted and modest" tax cuts.
In its submission to the Treasury, the CBI called on the chancellor to deliver "Plan A plus" to bolster growth and investment.
In the FT, Mr Fox said it was "intellectually unsustainable" that employment rights should stay untouched in the current economic climate.
In his most significant foray into front-line politics since his resignation last October, he called for employers' national insurance contributions to be cut across the board.
Mr Fox wrote: "To restore competitiveness we must begin by deregulating the labour market. Political objections must be overridden.
"It is too difficult to hire and fire, and too expensive to take on new employees.
"It is intellectually unsustainable to believe that workplace rights should remain untouchable while output and employment are clearly cyclical."
He added: "There is a strong argument for further public spending reductions - not to fund a faster reduction in the deficit, but to reduce taxes on employment.
"Although the coalition agreement may require the chancellor to raise personal tax allowances, he should use the proceeds of spending reductions to cut employers' national insurance contributions across the board.
"If that is deemed impossible, he should consider targeting such tax cuts on the employment of 16 to 24-year-olds, making them more attractive to employers."
BBC political correspondent Iain Watson says Mr Fox has gone on the attack - ostensibly his message is aimed at those on the left who oppose further deregulation of the labour market.
But he is also issuing a rallying cry for Conservative MPs, particularly those on the right of the party, who want the chancellor to cut business taxes in the Budget, our correspondent adds.
'Plan A plus'
CBI director general John Cridland said of its call: "The chancellor must use this Budget to score the growth and investment policy goals he put forward in his Autumn Statement.
"With our economy firmly under the international spotlight, there is no time to lose: Plan A plus must become a reality."
On Sunday, shadow chancellor Ed Balls called for "decisive action" to boost economic growth and offered suggestions for tax cuts in the Budget.
Mr Balls' ideas include a VAT cut, a 3p income tax cut for a year, bringing forward the planned personal allowance rise to £10,000 and higher tax credits.
No tax cut could mean "a permanent dent in our nation's prosperity", he said.
The Conservatives responded by saying excessive borrowing and debt under Labour had led to the current financial mess.
From BBC news