Thousands of officials and civil servants working across the public sector are paid by the taxpayer to work full time for their unions, new figures show.

Government figures will published on Monday will show that there are more than 16,000 full time union officials who are on the public pay roll.

The figure is far in excess of previous estimates. An investigation by the Telegraph in 2011 estimated the number to be around 1,785 public sector workers, costing tens of millions of pounds in wages.

Public bodies have a duty by law to start to publish the information by the end of July and are now committed to publish the information annually.

The issue rose to prominence in 2011 when Jane Pilgrim, an NHS worker who worked full time for health union Unison criticised the Government’s health policies.

The trawl of Government records shows there are 16,664 full time "Pilgrims" across police forces, NHS bodies, councils, and Government departments.

The actual figure is likely to be far higher because a wide range of public bodies are still to report their figures.

In Opposition the Tories pledged to clamp down on this so-called "facility time" - the official term for the practice of allowing staff to undertake trade union business during work hours.