Maltese Prime Minister Joseph Muscat told the nation Sunday night that he would resign in January following pressure from angry citizens for the truth about the 2017 auto bombing that killed a journalist.

Yorgen Fenech pleaded not guilty in a Valletta court on Saturday (November 30) to the charge and others related to the case such as membership of a criminal gang and conspiracy to cause an explosion. He was also arraigned on the further charge of promoting, organizing or financing a group with the intention of committing a crime. Shortly after the blast, three men were arrested for allegedly carrying out the actual bombing.

Magistrate Audrey Demicoli asked Fenech to enter pleas. They were arrested in December 2017 and pleaded not guilty in pre-trial proceedings.

Ten days earlier, Malta police stopped Fenech as he was sailing away from Malta on his yacht.

The murdered journalist's family say the prime minister has been left deeply compromised and should resign because he failed, for the past two years, to take action to clean up politics in Malta.

"But this weight pales into insignificance when compared to the weight that the family of Daphne Caruana Galizia had to shoulder", Muscat said.

Mr Muscat, in power since 2013, has said he will speak after the investigative case is complete.

Fenech has also requested a pardon, saying in court papers that he can give information on the plot involving the prime minister's former chief of staff Keith Schembri, former tourism minister Konrad Mizzi and Chris Cardona, who has suspended himself as economy minister.

Mr Fenech has been released under police watch, the Reuters news agency reports.

The two, along with Schembri, have said they are innocent of wrongdoing. The family reportedly believes the individual is responsible for her death.

Speaking yesterday for the first time since his arrest, he denied being the author of a type-written letter that Mr Fenech told police he secretly received after his arrest.

Three men - brothers Alfred and George Degiorgio and their friend Vincent Muscat, all in their fifties - have been charged with triggering the bomb in her auto. Caruana Galizia wrote about 17 Black less than a year before her death, linking its operation with Schembri and Mizzi. "And I will never accept that someone conveys a signal that in any way he or she is justifying this murder".

Before her murder, she linked both men to secret payments made by Mr. Fenech through a Dubai company called 17 Black.

Schembri has said that 17 Black had been a potential client for his business group.

Investigations into Caruana Galizia's murder intensified when a suspected middleman was pardoned on Monday. The project reported previous year that Malta's anti-laundering watchdog had identified Fenech as 17 Black's owner.

Fenech, who was re-arrested on Saturday, has not commented publicly on this.

Despite having previously expressed opposition to Malta's entry into the European Union, Muscat was elected to the European Parliament in 2004.

On September 20, the government announces a public inquiry into the killing, just ahead of the expiry of a three-month deadline by the Council of Europe to set up such an investigation.

Sources briefed on the murder investigation told Reuters that police regard Fenech as the mastermind of the journalist's killing.

Before she was killed, she had alleged that Schembri and Mizzi had been involved in corruption. It was unclear where and when the photo was taken.