A teachers union has written to the police commissioner requesting an investigation into former education minister Justyne Caruana and her permanent secretary Frank Fabri. 

Caruana resigned from the post on Wednesday, weeks after an ethics probe found she abused her position in awarding a contract to her close friend, who failed to do the job and then lied about it. 

The pressure is now on the permanent secretary of the department, Frank Fabri, who is also facing calls to resign because he signed off on the arrangement. 

Standards commissioner George Hyzler had suggested that a parliamentary committee consider whether to ask the police to investigate if a criminal offence has been committed.

Graham Sansone, executive head of the Union of Professional Educators (UPE), has written to police commissioner Angelo Gafà asking for an investigation into both Caruana and "other Ministry officials".

He attached the report and highlighted how Daniel Bogdanovic was paid for the work despite only carrying out a minimal part. 

"The said contract was signed by Dr Francis Fabri, Permanent Secretary on behalf of the ministry," Sansone points out in the letter.

"Payment to the named individual were issued...moreover the report and annexes indicate that the ministry was aware of the lack of competence of the named individual... and still proceeded to affect almost full payment," he writes.

The Hyzler report highlights the possibility of an investigation into a potential violation of articles 124 and 125 of Malta's criminal code. 

Those articles concern public officials taking a private interest in issuing orders or handing out contracts, and carry jail terms of up to six months for anyone convicted of breaching them.

Caruana has denied doing anything wrong and has said she will challenge the report in the constitutional court.