One in six Dutch local authorities are thought to have set up fake social media accounts so they can monitor potential trouble such as demonstrations and planned riots, the Volkskrant said on Tuesday.

The paper bases its claim on research by Groningen University and the NHL Stenden college,  which shows local councils are widely following Facebook groups, Twitter accounts and other social media.

But civil servants are often unaware they are breaking the law, which restricts the use of fake accounts to the police and security services, the paper said. In total, 156 of the 352 Dutch local authorities responded to the survey.

Almost one in six said they used fake accounts and in some cases, civil servants used fake names to infiltrate closed Facebook groups, the paper said.

Council officials also check for social security fraud via online market Marktplaats to see if people are earning on the side.

In total, 23 of the councils which responded stored the information in automated digital files.

Leiden University professor Bart Custers told the paper that using fake names, storing personal information and joining closed groups are a serious breach of privacy and ‘simply forbidden.’

‘Local councils should not be playing at being the police or security services,’ he said.

The Dutch local authorities association VNG said it could not yet react to the claims because it is carrying out its own investigation.

Last month, the NRC reported that the counter terrorism unit NCTV was also using fake accounts to analyse social media movements and track down potential trouble. This too is against the law.