David Cameron has waded into the Cabinet row over austerity, branding those calling for relaxation of spending restrictions "selfish".
The former prime minister's comments came amid pressure from a string of Government ministers to ease the 1% cap on pay rises for public sector workers.
Chancellor Philip Hammond last night insisted that the Government's approach had not changed, but said that the Treasury was "continually" assessing the balance between being fair to public servants and fair to the taxpayers who fund their wages.
Speaking at the Asian Leadership Conference in South Korea, Mr Cameron - who presided over a two-year public sector pay freeze before the introduction of the 1% cap in 2012 - rejected the idea that it was "generous" to give up on the principles of sound finance.
"The opponents of so-called austerity couch their arguments in a way that make them sound generous and compassionate," said the former PM.
"They seek to paint the supporters of sound finances as selfish, or uncaring. The exact reverse is true.
"Giving up on sound finances isn't being generous, it's being selfish: spending money today that you may need tomorrow."
Several Tory MPs have put pressure on Theresa May and Mr Hammond to lift the pay cap after the party lost its majority in the General Election to anti-austerity Labour, which has pledged to scrap the 1% ceiling.
Health Secretary Jeremy Hunt said he had "a great deal of sympathy" for nurses' demands for higher rises, while sources said that Foreign Secretary Boris Johnson privately backs a wage boost for public sector staff.
And on Monday, policing minister Nick Hurd told the House of Commons there was an "active discussion" under way to ensure frontline workers are paid fairly.
Mr Hammond told business leaders on Monday evening that there had to be a "grown-up" debate about how to meet demands for improved public services.
He said: "Our policy on public sector pay has always been designed to strike the right balance between being fair to our public servants and fair to those who pay for them," he told a CBI dinner.
"That approach has not changed; and we continually assess that balance.
"But we do, of course, recognise that the British people are weary after seven years' hard slog repairing the damage of the Great Recession."
The Fire Brigades Union (FBU) said that an offer from employers worth 2% on basic pay this year and a potential 3% from April 2018 showed that the pay cap was "dead in the water".
But Downing Street insisted that firefighters' pay was a separate issue from that of other public sector workers, as central government has no role in negotiating or agreeing the figure.
Increasing public sector pay would boost the earnings of 5.1 million workers, including 1.6 million in the NHS and 1.5 million in public education, according to the Institute for Fiscal Studies. It is likely to cost billions of pounds.
Labour seized on an academic study which showed school teachers saw a drop in average earnings in real terms from £25 an hour in 2005 to £22 an hour in 2015, while police officers saw hourly earnings fall from £20 to £18 and doctors from £38 to £30.
The report to the Office of Manpower Economics found nurses' median hourly earnings were effectively stagnant over the course of the decade from 2005-15, starting off at £16, rising to £17 by 2010 before falling back to £16.
Shadow chancellor John McDonnell said: "This a damning report that reveals the harsh and unfair reality of the Tories' pay freeze on hard-working public sector workers.
"The fact that some of the pillars of our community and the public sector such as teachers, doctors and police officers are seeing their pay cut exposes the double standards of a Government that likes to praise their work but will not actually truly reward it."