The government's claim that it would cost £1,000 per household to meet unions' pay demands may be an underestimation, a senior cabinet minister has warned.
Oliver Dowden said matching pay rises with inflation would only send prices up further.
The chancellor of the duchy of Lancaster told the BBC's Sunday With Laura Kuenssberg programme the country must stabilise its public finances first.
He said that while most unions are basing their pay requests on CPI inflation (currently at 10.7%), nurses – who staged a mass walkout on Thursday and have threatened further strike action – are asking for a rise that is 5% above the RPI inflation rate of 14.2%, amounting to a demand of over 19%.
Dowden said that, for this reason, it could cost the country even more than the estimated £28 billion to meet unions' demands.
He said: "I would love to give nurses an enormous pay rise. The reason why we're not doing this is because our duty is to everyone, public and private sector, to make sure we have stability in our public finances... We don't want to put that at risk."
However, Kuenssberg asked why the independent Institute for Fiscal Studies (IFS) predicts that it would cost the public a significantly lower £14 billion to meet public sector demands.
Many economists expect inflation to drop in 2023, suggesting that public sector pay rises will be lower in real-terms than the government has claimed.
Kuenssberg also pointed out that Downing Street has based its estimation on the rate for October – a 41-year high of 11.1% – rather than using an average, suggesting it isn't painting an accurate picture.
Insisting the government's projections are not "misleading", Dowden said: "We can only take the number that we have now.
"The inflation number we have now, it was a bit over 11% last month, it’s dropped very slightly to 10.7% – it's reasonable to take that number and project it forward and say what it will cost next year.
"If they are saying that they want to have a lower number, then that is a different proposition, and that's not what they're coming to the table with."
It comes as ambulance crews in England prepare to walk out for two days on 21 and 28 December in a dispute over pay.
Dowden said the government had been "working relentlessly" to ensure that anyone with serious or life-threatening injuries could still rely on the ambulance service during these strike days.
Read more: What strikes are happening in December?
But he suggested that those with more minor injuries should dial 111 instead of 999 and that they should aim to make their own way to hospital if they are able to do so.
Calling for workers to call off the strikes and to "give families a break this Christmas", he said: "It really is in the unions' hands.
"I would urge the unions to be reasonable, to engage both in terms of calling off this strike, but also in terms of the kind of level of service they’re willing to provide."