Joseph Muscat will return as PN's "nightmare", PL's Jason Micallef warned on Thursday.

His claim comes a day after the former prime minister's lawyers relentlessly questioned whether a court-appointed expert for the Vitals inquiry was qualified for her role and asked for her qualifications as an accountant.

Miroslava Milenovic, who was appointed by the court as a forensic accountant, told the court on Wednesday she had more than 20 years of experience working as an accountant and is a certified fraud specialist. 

After being pressed numerous times by defence lawyer Vince Galea , Milenovic said she never obtained a warrant as an accountant, and that she never mentioned it to the magistrate when she was appointed as she was never asked for it. 

On Thursday, Micallef called the inquiry "amateurish".

Micallef was recently appointed as the PL's "special delegate on the implementation of the electoral manifesto' and he will report directly to the party's central administration. 

He told his Facebook followers that the inquiry, "which cost taxpayers €11 million" was aimed at crucifying Muscat and his family, as payback for destroying the PN during his leadership.

He warned there will be a time when Muscat will return and become the Opposition's nightmare.

Muscat will also be a nightmare for the "PN branch and extremist PN group 'Repubblika' and others who felt they should distance themselves from him in the past years".

When Muscat returned, Micallef promised, would also be there together with his others who continued supporting the ex-premier.