The NGO Repubblika has called for the Auditor General to investigate ministers' use of public funds on their personal social media pages. 

In a letter to Prime Minister Robert Abela, the rule of law lobby group said the government had spent more than a million euros in social media advertising between 2013 and 2017. 

They also called for ministers found to have misused public funds to pay back any money spent on personal social media advertising. 

An investigation by Standards Commissioner George Hyzler found that four ministers - out of five randomly selected for the probe - had incorrectly used public resources for material uploaded to their private Facebook pages.

Repubblika said the inquiry had left open the possibility of worse offenders than those investigated. 

The NGO also criticised the fact that three of the five ministers had not responded to the Standard Commissioner's request for information. 

"We are convinced that this is an extremely serious matter in a democratic society, that cannot be allowed to continue as if nothing had happened."

The Standards Commissioner's investigation found that Infrastructure Minister Ian Borg, Environment Minister Aaron Farrugia, Economy Minister Silvio Schembri and Finance Minister Edward Scicluna all incorrectly used public resources.

Education Minister Owen Bonnici was not found to have misused public resources. 

The government has since agreed to new guidelines proposed by the Commissioner to prevent such misuse.