Promoter of Justice Gian Pietro Milano said the funds (some $2.1 million) were part of a total of around 13 million euros frozen between 2013 and 2016.

Last year the Holy See's financial watchdog, the Financial Information Authority (AIF), said it had closed nearly 5,000 suspect accounts as part of a three-year examination of the once murky Vatican bank.

The Institute of Religious Works (IOR), as the bank is known, became notorious around the world because of a 1980s scandal centred on the death of banker Roberto Calvi, whose corpse was discovered hanging under Blackfriars bridge in London.

The AIF was established in 2010 by now-retired Pope Benedict XVI to bring the Vatican's financial institutions into line with international standards designed to reduce the risk of accounts being used for nefarious purposes.

Francis boosted the AIF's power after his election in 2013.

The Vatican had also signed up for external evaluation by Moneyval, a European body that combats money laundering and the financing of terrorism.

Moneyval reported in 2015 that the Vatican had addressed most of itsstructural weaknesses.

But it also questioned why no indictments or prosecutions had ensued as a result of the evidence of wrongdoing gathered and handed to prosecutors.

Milano said 23 cases of suspected financial crimes had been flagged up by the AIF between 2012 and 2016.

Six had since been dismissed, while 17 were still being investigated.