The former chief of staff of Malta’s government was arrested over the murder of journalist Daphne Caruana Galizia on Wednesday as suspects reportedly began pointing the finger at each other and opposition MPs renewed calls for the prime minister to resign.

Opposition politicians walked out of parliament in Valletta, saying the Labour government of Joseph Muscat had lost all legitimacy.

They accused Mr Muscat of trying to shield his chief of staff, Keith Schembri, right up until Mr Schembri’s resignation on Tuesday.

Mr Schembri, one of the prime minister’s closest allies, had been chief of staff since 2013.

Mr Schembri resigned after he was reportedly named as a “person of interest” in the investigation by Yorgen Fenech, a multi-millionaire businessman who was arrested last week as he tried to leave Malta on his luxury yacht. Both have denied any wrongdoing.

Adrian Delia, the leader of the opposition Nationalist Party, said his MPs would no longer engage with a “government that has lost its legitimacy.”

He accused the prime minister of “not having the slightest decency to sack” Mr Schembri.