The government has been accused of using “scare tactics” to frighten the public about workers going on strike.
Cabinet minister Oliver Dowden on Sunday was accused of pushing misleading figures about how much it would cost to meet nurses’ and other workers’ demands.
Ministers have repeatedly claimed households would be worse off by £1,000 unless it cuts the wages of public sector workers in real terms.
But fact-checking organisations and economic think tanks like the Institute for Fiscal Studies have said the number is too high.
It comes amid walkouts across the country by nurses, rail staff, postal workers, and civil servants, among other sectors.
Most workers on strike are asking for pay rises to keep up with rising prices and avoid their salaries being eroded in real terms – but the government says it would be too expensive.
An estimated 10,000 NHS nurses in England, Wales and Northern Ireland plan to walk out again on Tuesday after staging stoppages on Thursday.
On Monday they are expected to be joined by driving test examiners in parts of northern England, as well as localised walkouts by staff at the Department for Work and Pensions.
Ambulance staff in England and Wales are planning to strike on Wednesday and on 28 December, while Border Force staff working in passport control are also walking out in periods over Christmas.
And rail strikes are affecting train services across much of the holiday period.
Speaking on Sunday Mr Dowden told the BBC's Sunday With Laura Kuenssberg programme it would not be responsible to increase wages in line with inflation.
“We will be resolute in response to this because it will be irresponsible to allow public sector pay and inflation to get out of control and we owe a wider duty to the public to make sure we keep our public finances under control,” he told the broadcaster.
But responding to Mr Dowden’s comments, Liberal Democrat Cabinet Office spokesperson Christine Jardine said: “In the week before Christmas we need more humanity not less from Oliver Dowden and his government.
"Sitting down with the nurses and discussing pay is the obvious move right now. Instead he spent this morning playing scare tactics with the public and playing politics with the strikes.
"This government has spent the past year giving tax breaks to the banks and leaving the NHS and nurses struggling, this has to change to get a fair deal for everyone.”
Nurses are asking for a pay rise to stop their pay being eroded by inflation, and then a 5 per cent rise on top of this to increase their wages. There are a record high of nearly 50,000 unfilled nurse vacancies across the country, with hospitals struggling to recruit to replace people leaving the profession.
Arrangements have been made for 1,200 troops from the army, navy and RAF to help mitigate disruption from widespread walkouts over the festive period, with more than 1,000 civil servants also drafted in.
Serious doubt has been cast on the government’s figure of a £1,000 cost of meeting the wage demands. The figure relies on a monthly estimate of inflation that is unlikely to reflect the real cost over the whole of next year. It also assumes the cost would be shared evenly rather than through a progressive tax system, and does not take into account the extra tax paid by public sector workers earning more.
An estimate by the BBC puts the number at £820 per household, even before the increased tax take and distribution of costs is taken into account.
Quizzed on the miscalculation Mr Dowden said the number was however “justified”.
A Treasury spokesperson stood by the £28bn figure, saying: “It would cost £28bn to increase all public sector workers’ pay by inflation – this would illustratively cost each household in the UK around £1,000.”
