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VALLETTA (Reuters) - Three men accused of the murder of an anti-corruption journalist six months ago must stay in prison until their trial, a Maltese magistrate ruled on Thursday.

Brothers Alfred Degiorgio and George Degiorgio and Vince Muscat were arrested in early December, after a car bomb killed Daphne Caruana Galizia as she drove out of her home on Oct. 16.

They have pleaded not guilty, and their lawyers argued they should be freed until a date for their trial is set. The court rejected the request, citing the seriousness of the crime, protection of public order and a risk that the accused might commit other crimes.

The decision came as a group of local and international media groups, including Reuters, began following up stories covered by Caruana Galizia, in an initiative called the Daphne Project.

Read the Reuters special report here.

On Thursday, Maltese Economy Minister Chris Cardona denied he met one of the murder suspects in a bar in Siggiewi, in the south of Malta. Some of the Project journalists reported such a meeting, citing a secret recording of a witness at the bar and another anonymous source. Reuters did not report the allegations and has not verified those claims.

In a statement to Reuters, Cardona had said he did not recall talking to any of the three suspects. On Thursday, when asked by the Times of Malta if he had ever been at the bar while any of the accused men were there, Cardona said no.

Opposition leader Adrian Delia, speaking in parliament on Wednesday, said the claims against the minister were harmful to Malta and he needed to explain himself.

Cardona had been a frequent target of Caruana Galizia, and he had sued her after she accused him of visiting a brothel while on official business abroad. He has denied the accusation.