Italy is about to begin a national debate about legalizing marijuana, and one senior official is promising that, should the country forge ahead in regulating and taxing pot, it could be a blow to the Islamic State and the mafia at the same time.

Legislation will be introduced in the Italian parliament next week to remove criminal prohibitions on marijuana, let Italians grow up to five plants at home, and buy cannabis from a state-run monopoly.

If that bill passes, the smuggling route from the northern tip of Africa could be disrupted, according to Franco Roberti, the country's top prosecutor in charge of fighting both the mafia and terrorism.

"Decriminalization or even legalization would definitely be a weapon against traffickers, among whom there could be terrorists who make money off of it," Roberti told Reuters in April.

Roberti says this is because the mafia and "suspected terrorists" share smuggling routes in North Africa, and collaborate to move product into Italy and then throughout Europe.

"The main smuggling route for North African hash — compressed cannabis resin — now runs from Casablanca, Morocco, through Algeria, Tunisia to Tobruk in eastern Libya," according to Roberti.

Sirte, a city in Libya along that route, has been under IS' control since February 2015, though anti-IS rebels are now attempting to regain control of the group's last stronghold in the country.

Using or selling drugs is strictly prohibited in IS-controlled territory, with users being publicly whipped in the past, and traffickers executed.

Regardless, drug sales make up nearly seven percent of IS' revenue — over $4 million per month, according to an estimate from financial agency IHS Markit, released in April.

Roberti's call to legalize marijuana comes as law enforcement agencies in Italy have begun to view the fight against terror and organized crime as one and the same, with once separate strategies to fight the groups converging. In February 2015, Roberti's organized crime unit was given the new responsibility of leading investigations into terrorist groups. The two initiatives even share a database.

This decision was made because organized crime and terror groups function in a similar manner, according to Roberti, who wrote extensively about this connection in a new book, published in April.

"International terrorism finances itself with criminal activities that are typical of the mafia, like drug trafficking, smuggling commercial goods, smuggling oil, smuggling archaeological relics and art, kidnapping for ransom, and extortion," Roberti told Reuters.

In some cases, namely drug trafficking and gun running, the two factions end up working together, leading to increased profits for both.

IS uses its cash to purchase arms, pay soldiers' salary, and fund propaganda to lure potential recruits to join the cause, so Roberti believes the group's ability to retain territory in Libya can be partly attributed to the funds acquired through collaboration with organized crime in Italy.

The public is largely in support of the proposed law, as 73 percent support marijuana legalization, and 83 percent find current drug laws in Italy to be ineffective.

The legislation, put forward last July by Cannabis Legale, an interparliamentary group, has already attracted the support of at least 220 MPs and 73 Senators — and that's before the motion has even come forward in the 635-member lower house — meaning the bill does have a chance of making it into law.

Estimates on the size of the Italian black market for marijuana are hard to pin down, but estimated guesses from both law enforcement and private groups put the figure into the tens of billions of dollars per year. For a country struggling with a debt load that is 33 percent larger than its GDP, that tax revenue could be hugely significant.