Dossiers were compiled by 15 departments after scouring social media activity to vet people invited to speak at official events
The guidelines are designed to prevent anyone who has criticised the government in the previous three to five years from speaking at government-organised conferences and other events.
In September, the Observer revealed how three early-childhood education experts discovered that the Department for Education tried to cancel invitations for them to speak at government-funded events because they were judged to have been critical of government policy. Many more education experts and school staff have since uncovered files of their critical social media posts held by the department.
However, it has now become clear that the practice is widespread across government and is probably targeting large numbers of individuals. The scale of the monitoring was uncovered by human rights experts at law firm Leigh Day and shared with the Observer.