ROME, May 10 (Xinhua) -- Italian anti-terrorism units have arrested 14 Syrian and Moroccan nationals who financed an Islamist extremist group in war-torn Syria by laundering money from illegal immigration, prosecutors said in a statement Thursday.

The network funneled over 2 million euros (2.40 million U.S. dollars) from Italy and other European countries to the al Qaeda-affiliated group Jabhat al-Nusra in Syria through the so-called "hawala" informal remittance system.

The system leaves no paper trail and is hard to trace because it takes place outside the banking and money transfer sectors, finance police said in a statement.

"The investigation uncovered ... a criminal structure of Islamic origin based in (the northern Italian area of) Brianza and which actively promoted illegal immigration into Europe, incessantly raising and transferring funds through unconventional channels such as hawala," the statement said.

National Anti-Mafia and Anti-Terrorism Prosecutor Federico Cafiero de Raho told a televised press conference that the money "came largely from illegal immigration".

"Previous claims that there is no connection between migration and terrorism have been contradicted," De Raho said.

"We don't have evidence that this network brought foreign fighters into Italy as migrants, but it is true that part of the funds this network managed came from clandestine immigration and they were used to support terrorism."

In one operation, Italian investigators "dismantled a transnational criminal organization made up of 10 Syrians" that laundered money in Hungary, Italy, Sweden, and Turkey. Two of those suspects have been charged with terrorist financing.

In a parallel operation, police arrested four Syrian and Moroccan "militants ... accused of being part of a support cell" for Jabhat al-Nusra in Syria. They are accused of terrorist criminal association, terrorist financing, and illegal financial intermediation.

The arrests took place in two separate dawn operations, and 20 homes were searched in the Emilia Romagna, Lombardy, Sardinia, and Veneto regions.

"The arrested subjects sent money...mainly to Turkey and Syria using an ancient, difficult to trace system (hawala). Investigators uncovered solid evidence...thanks to intelligence activities and international cooperation," state police tweeted.

Investigators used wiretaps and undercover officers to dismantle the network, the finance guard said.

In a statement, Interior Minister Marco Minniti praised today's operation, which he said "uncovered and neutralized potentially hostile structures".