The findings, from the Universities and Colleges Employers Association (UCEA), show that the pay of staff has dropped by around 17% in real-terms since 2009.

UCU said it was shocked and disappointed that UCEA has tried to spin the findings to suggest pay has not fallen so sharply. In its presentation of the data, UCEA has chosen to show findings only from 2013 and cherry picked the information used to calculate the figures.

However, table 8 of the report shows that pay has actually dropped by around 17% since 2009 when using the retail price index (RPI). Last month, Chancellor Sajid Javid rejected a call to stop using RPI, saying to do so risked damaging the economy and the public finances.

The union says that staff pay has actually fallen by around 20% in the last decade as pay awards in higher education have resulted in a cumulative increase of 11%. In the same time period, the RPI index has increased by 31.8%. Meaning staff in higher education have seen the value of their pay decline by 20.8% since 2009.

The union's analysis looked at the cumulative impact of the overall pay awards each year versus inflation, while the UCEA analysis looked at certain spine points. UCU said whichever method was preferred, staff pay had dropped by a minimum of 17% since 2009.

UCU members at 147 universities are currently being balloted for strike action over pay and workloads. UCU members at 69 institutions are also being balloted for action over changes to the Universities Superannuation Scheme.

UCU general secretary Jo Grady said: 'At last the employers have revealed the full extent of the reduction in the value of university staff pay. We believe the true decline over the past decade is over 20%, but whichever way you look at it staff pay has plummeted. Universities need to immediately take steps to reverse the decade of decline.

'It is quite remarkable that the employers have tried to spin a different story when the figures are available in their own report. UCU members currently being balloted for strike action over declining pay will be shocked and disappointed that universities could make such misleading claims. Cherry picking a later starting date and the information used to work out the figures cannot alter the fact that staff pay has declined.'