The Council of Europe's Human Rights Commissioner also called on Malta to strengthen the protection of journalists.
ADVERTISEMENTMalta has been urged to redouble efforts to investigate the 2017 murder of Daphne Caruana Galizia.
The Council of Europe's Commissioner for Human Rights, Dunja Mijatović, has also called on Maltese authorities to strengthen the protection of journalists.
It came in a report prepared by Mijatović after a visit to Malta in October but which was only published on Tuesday.
"The Commissioner calls on the Maltese authorities to continue their investigations to identify anyone involved in the murder," it read.
Those responsible for the murder must be "held accountable" to the law, the report added.
One man has already been imprisoned for 15 years for murdering the investigative journalist, while two other suspected hitmen are awaiting trial.
The 53-year-old reporter was killed in a car bomb attack in October 2017, while she was investigating corruption with Maltese authorities.
Business tycoon Yorgen Fenech is accused of ordering and paying for her murder and also faces a life sentence if convicted. He denies the charges.
Another suspect, the alleged "middleman", agreed to reveal details of the plot to kill the investigative journalist and was granted a pardon.
The killing of Caruana Galizia in a car bomb rocked the Mediterranean island and sent shockwaves across the European Union.
An independent inquiry last year found that Malta's government must "bear responsibility" for her death, even if it did not play a direct role.
Malta's former Prime Minister Joseph Muscat resigned in January 2020 following Fenech's arrest and widespread protests.
Mijatović said the murder of Caruana Galizia has "highlighted the urgent need for measures to protect journalists in Malta".
She called on Malta to "act quickly to implement" the reforms that were recommended of the independent inquiry.
The Council of Europe report also severely criticised Maltese authorities for their policy towards migrants trying to reach Europe via the Mediterranean Sea.
But the report did acknowledge that the country had taken "substantial steps" towards women's rights and gender equality in recent years.