Ten international media freedom organisations expressed "deep concern" over the lack of progress in the investigation into the murder of Maltese journalist Daphne Caruana Galizia.

More than three months after the journalist's assassination there are no public indications to suggest that the authorities have identified the people who commissioned, planned or orchestrated the murder.

Three suspects have been arrested in connection with her murder.

Watch: Three accused of Daphne Caruana Galizia murder as widower looks on

The organisations are partners of the Council of Europe Platform for the Promotion of Journalism and the Protection of Journalists. The organisations are Article 19, the Association of European Journalists, the Committee to Protect Journalists, the European Federation of Journalists, the Index On Censorship, the International Federation of Journalists, the International News Safety Institute, the International Press Institute, PEN International and Reporters Without Borders.

Ms Caruana Galizia was murdered in a car bomb explosion last October, sparking worldwide anger and condemnation.

"Her death raised concerns not only about protection of critical journalists but also about the rule of law and corruption in Malta," they said.

Her death raised concerns not only about protection of critical journalists but also about the rule of law and corruption in Malta

"We remind the government of Malta and all concerned that guidelines related to judicial follow-ups to the killing of journalists approved by the Committee of Ministers of the Council of Europe in April 2016 state that “investigations must be effective to maintain public confidence in the authorities’ maintenance of the rule of law and to prevent any appearance of collusion in or tolerance of unlawful acts.”

The guidelines also recommend that “investigations should be subject to public oversight, and that the victim's next of kin must be involved in the procedure to the extent necessary to safeguard their legitimate interests.”

"We believe that, given the profile of the crime and the issues of corruption Daphne Caruana Galizia had worked to uncover, the investigation into her assassination demands the continued scrutiny of the international community."

They joined Ms Caruana Galizia’s family in calling on the parliamentary assembly of the Council of Europe to appoint a special rapporteur to monitor the ongoing murder investigation and make an assessment of the contextual circumstances that led to her murder.

The killing of Ms Caruana Galizia demonstrated the dangers which journalists around Europe faced last year.

In 2017, the organisations submitted 130 alerts concerning 29 countries, confirming last years’ trends of the wide geographic spread of threats to media freedom. In 60% of the alerts in 2017, the State was the source of the threat.

Fewer than 30 per cent of the alerts passed on to member states in 2017 received a State reply.