FLORENCE, Italy, June 20 – Prosecutors in Florence have formally asked for Bank of China's Milan branch and 297 individuals, mostly Chinese living in Italy, to be tried for smuggling money and other crimes.

The document, a formal request by the prosecutor seen by Reuters on Saturday, stems from an investigation called "River of Money" that started in 2008 and points to the growing influence of Chinese criminal groups in Italy's Tuscany region.

The investigating prosecutors allege various crimes, including money laundering and tax evasion, according to the 170-page document signed by Florence prosecutor Giulio Monferini.

Investigators said money sent to China through agencies of the Money2Money (M2M) transfer service in several Italian cities included proceeds from crimes such as counterfeiting, embezzlement, exploitation of illegal labour and tax evasion.

According to the document, more than 4.5 billion euros ($5.1 billion) was smuggled to China from Italy between 2006 and 2010 using M2M. It said 2.2 billion euros of that had been sent via the Bank of China's (BOC) Milan branch.

BOC received more than 758,000 euros in commissions on the transfers, according to the prosecution request.

The bank, China's fourth-biggest, was included in the investigation because under Italian law it has administrative responsibility for four officials among the accused who worked at its Milan branch during the period under investigation.

The four officials are accused of failing to report suspicious transactions and of other actions that helped to conceal the origin and destination of the funds and facilitated Money2Money's money laundering activities.

A Bank of China executive said she was unable to comment, and referred a Reuters phone call requesting information to the bank's office in Italy.

Calls to the lender's Milan branch on Saturday were answered by an automated message. No contact details could be found for Money2Money's offices.

A judge will now review the prosecutor's request and decide whether to file any formal charges.

The money was sent from Chinese citizens, living mainly in the Tuscan cities of Florence and Prato, without properly identifying the senders or using fictitious names, the prosecutor's request said.

It is not clear who in China received the money, which was split into small sums to avoid suspicion, the document said.

The investigation was launched in 2008 by Pietro Suchan, the first Italian investigating magistrate to tackle Chinese crime.

The Chinese underground economy in Tuscany was brought into focus in 2013 when a fire killed seven workers as they slept in cardboard cubicles at a workshop in Prato, which has one of the highest concentrations of Chinese immigrants in Italy.

Prato is at the centre of a network of often-illegal workshops that make garments for export and for retailers. ($1 = 0.8807 euros)