ROME, SEPT. 7 -- When the Italian Navy arrives in the Persian Gulf, the mines it will try to sweep out of the way of Italian ships most likely were manufactured in Italy and illegally supplied to Iran by Italians.

This revelation follows a decision Friday by the Italian government to send a mine-sweeping force to the gulf to protect Italian shipping and the arrests during the weekend of 33 persons in an arms sale caper that a newspaper here calls "our own Irangate."

The story, as it unfolded in the Italian press, involves a rich, well-known industrialist, scion of one of Italy's leading capitalist clans; a secret middleman of dual nationality; illegal sales of arms to Iran via third countries; a raid by customs agents of a rusting Lebanese freighter allegedly carrying arms for terrorists linked to the Abu Nidal group and drugs for the Mafia; and revealing secret documents left behind in a hastily vacated hotel room.

On the basis of investigations over the past month by Augusto Lama, investigating magistrate of the Tuscan port city of Massa, the city's public prosecutor, Giovanni Panebianco, on Saturday issued 45 arrest warrants against those believed to have been involved. Italian police arrested 33 of the 45, including the prominent arms manufacturer Ferdinando Borletti, 65, and his son Giovanni, 33.

The senior Borletti, grandson of the founder of Italy's popular Rinascente department store chain, heads a company in northern Italy called Valsella Meccanotecnica that specializes in manufacturing munitions, especially mines.

Half the company is owned by another firm, Gilardini, a subsidiary of the Fiat conglomerate. Fiat issued a statement today denying any responsibility for Valsella's management and operations. The elder Borletti sits on Fiat's board of directors.

The Borlettis and others are accused not only of having been involved in illegal arms shipments to Iran, but also of associating with suspected Mafia figures and unnamed Arab terrorists believed to be linked to the Abu Nidal group.

The catalyst for the arrests was the interception earlier in the week by the Italian Customs Service of a dilapidated Lebanese-registered freighter, named the Boustany I, off the Italian Adriatic port of Bari. Customs agents found arms on board the Boustany, including U.S.-made antiaircraft rockets, grenade launchers and antitank bazookas. They also found five pounds of refined heroin and 55 pounds of Lebanese hashish.

According to judicial sources in Massa, the Boustany, captained by a Syrian, Samir Boutros, was headed for a port near Massa presumably to pick up a cargo from Valsella, which had supplied the ship in the past.

Italian authorities immediately arrested Boutros, his 16-man crew and a mystery Arab passenger with a false passport, according to judicial sources here. The ship was impounded pending further search for more arms and drugs.

Police also learned that Aldo Anghessa, 45, a reputed middleman in the clandestine arms commerce between Italy and the Middle East who holds Italian and Swiss citzenship, had been in Bari awaiting the ship's docking.

According to sources close to investigating magistrate Lama, police raided Anghessa's hotel room, but he had fled, leaving behind a suitcase full of documents that detailed trade in mines between the Valsella arms firm and Syria, which apparently transshipped the mines to Iran.

Lama claims that as a result of those sales Valsella received another order from Syria for 2 million antipersonnel, antivehicle and antiship mines earlier this year, prompting Valsella to order a production increase in February.

According to sources in the prosecutor's office, Valsella sold 30,000 mines to Syria in 1986. Because there was an Italian arms embargo against Syria, a Spanish company in Barcelona provided an end-user certificate for the mines, saying the mines were destined for the Nigerian Army. But judicial sources here said the mines did not go to Nigeria, but rather to Syria and then to Iran.

Among those arrested were the directors of a shipping company in the Tuscan port of La Spezia that apparently arranged for the loading of the arms shipments and an export-import house in nearby Marina di Carrara that apparently handled the paper work in the shipments.

According to investigators, the prosecutor's office claims to have evidence that the arms were being brought to Italy by the ship's crew for Arab terrorists in Italy who are possibly linked to the Abu Nidal group, according to investigators.

The investigators said the drugs were destined for a Mafia family based in Trapani, Sicily. They said the same ships -- they claimed seven were involved -- allegedly bringing in illegal arms for terrorists and drugs for the Mafia were used to carry the illegal arms shipments to Syria.

The man who is probably in a position to know, Aldo Anghessa, has disappeared. The national police, the Carabinieri, have launched a nationwide manhunt for him.

Prime Minister Giovanni Goria's government is bracing for a parliamentary debate this week on its decision to send a mine-sweeping force to the Persian Gulf. The naval deployment is expected to begin in about a month.

{Meanwhile, in Tokyo, Japan's shipping industry and its seamen agreed Tuesday to end their four-day-old ban on sailings into the Persian Gulf, Reuter reported, quoting shipping sources. The ban was announced last week after a Japanese tanker was hit by Iranian rockets.}