VALETTA (REUTERS) - Lawmakers from Malta's ruling Labour Party stood by Prime Minister Joseph Muscat on Sunday (Dec 1), but did not indicate what he may do next as he faces pressure to quit amid a crisis sparked by the investigation into a murdered journalist.

The party's parliamentary group met for four hours, saying afterwards that lawmakers gave "unanimous support to all decisions which the Prime Minister will be taking".

Calls for Mr Muscat to step down grew after the probe into the 2017 car bomb killing of anti-corruption journalist Daphne Caruana Galizia led to charges on Saturday against a prominent businessman with alleged ties to ministers and senior officials.

Yorgen Fenech, 38, was taken to a Valletta court late on Saturday and charged with complicity in the murder. He pleaded not guilty to that and other charges.

The Prime Minister was thought to be preparing to announce his departure but seeking to stay in office until a successor is chosen, according to local media and government officials close to Mr Muscat.

Those same sources said he is likely to stay on until the party holds a leadership election in mid-January.

Fenech was charged after the government turned down his request for immunity from prosecution in return for revealing information about the murder plot and about alleged corruption involving Mr Muscat's former chief of staff Keith Schembri and former Tourism Minister Konrad Mizzi, among others, court filings showed.

Mr Schembri and Mr Mizzi resigned on Tuesday and Mr Schembri was interrogated for two days by police before being released without charge.

Mr Schembri has denied any wrongdoing. Mr Mizzi on Tuesday denied any business links with Fenech and any wrongdoing.

Maltese civil society organisations were due to hold a protest in Valetta, the capital of the tiny Mediterranean archipelago, on Sunday afternoon to call on Mr Muscat to go immediately.

"This is far from over. This is just the beginning. Joseph Muscat is still put, still protecting his best friend Keith Schembri. Because by protecting Schembri, Muscat is protecting himself," activist group Repubblika, one of the organisers of the protest, said on Sunday .

"We must keep up the pressure, The truth is coming out. Now we must strive for justice," it added.

Ms Caruana Galizia's family called on Saturday for Mr Muscat to step aside.

Critics are angry with Mr Muscat for sticking by Mr Schembri, an old friend since school, and including Mr Schembri in security briefings on the murder investigation even after Fenech was identified both as a suspect in the murder and an associate of Mr Schembri.

CARDONA RETURNS

The Labour Party statement after its meeting on Sunday also said Mr Chris Cardona, the economy minister who suspended himself from his duties on Tuesday after having been mentioned by a suspect in the investigation, has now been reinstated in his position.

Mr Cardona has denied any involvement in the plot and has denied any corruption or wrongdoing.

Ms Caruana Galizia had reported that Mr Schembri and Mr Mizzi had set up secret companies in Panama.

She also reported how another company, called 17 Black, was meant to be a vehicle to deposit funds into those companies.

Following her murder, an investigation by Reuters and Times of Malta showed Fenech as having been the owner of 17 Black.

Mr Mizzi has denied any business ties to Fenech or knowledge of 17 Black or any criminal activity.

Mr Schembri has always denied any wrongdoing. Speaking on Saturday for the first time since his arrest, he denied being the author of a type-written letter that Fenech told police he secretly received after his arrest.

Fenech said the letter told him to pin the blame for the murder on another government minister.

"I immediately denied that the letter came from me when the police were interrogating me and I stand by that completely," Mr Schembri told the Times of Malta.