During his more than four decades in power, Moammar Gadhafi of Libya was North Africa’s outrageously self-styled arms benefactor, a donor of weapons to guerrillas and terrorists around the world fighting governments he did not like.

Even after his death, the colonel’s gunrunning vision lives on, although in ways he probably would have loathed.

Many of the same people who chased the colonel to his grave are busy shuttling his former arms stockpiles to rebels in Syria. The flow is an important source of weapons for the uprising in the Levant and a case of bloody turnabout, as the inheritors of one strongman’s arsenal use them in the fight against another.

Evidence gathered in Syria, along with flight-control data and interviews with militia members, smugglers, rebels, analysts and officials in several countries, offers a profile of a complex and active multinational effort, financed largely by Qatar, to transport arms from Libya to Syria’s opposition fighters. Libya’s own former fighters, who sympathize with Syria’s rebels, have been eager collaborators.

"It is just the enthusiasm of the Libyan people helping the Syrians," said Fawzi Bukatef, the former leader of an alliance of Libyan brigades who was recently named ambassador to Uganda, in an interview in Tripoli.

As the United States and its Western allies move toward providing lethal aid to Syrian rebels, these secretive transfers give insight into an unregistered arms pipeline that is difficult to monitor or control. And while the system appears to succeed in moving arms across multiple borders and to select rebel groups, once inside Syria the flow branches out. Extremist fighters, some of them aligned with al-Qaida, have the money to buy the newly arrived stock, and many rebels are willing to sell.

For Russia — which has steadfastly supplied weapons and diplomatic cover to President Bashar Assad of Syria — this black-market flow is a case of bitter blowback. Many of the weapons Moscow proudly sold to Libya beginning in the Soviet era are now being shipped into the hands of rebels seeking to unseat another Kremlin ally.

Those weapons, which slipped from state custody as Gadhafi’s people rose against him in 2011, are sent on ships or Qatar Emiri Air Force flights to a network of intelligence agencies and Syrian opposition leaders in Turkey. From there, Syrians distribute the arms according to their own formulas and preferences to particular fighting groups, which in turn issue them to their fighters on the ground, rebels and activists said.

Qatari C-17 cargo aircraft have made at least three stops in Libya this year — including flights from Mitiga airport in Tripoli on Jan. 14 and Feb. 1, and another that departed Benghazi on April 16, according to flight data provided by an aviation official in the region. The planes returned to Al Udeid Air Base in Qatar. The cargo was then flown to Ankara, Turkey, along with other weapons and equipment that the Qataris had been gathering for the rebels, officials and rebels said.

Last week the Obama administration announced that it had evidence that Assad’s military had used sarin nerve agent in multiple attacks, and that the United States would begin providing military aid to the rebels, including shipments of small arms.

In doing so, the United States could soon be openly feeding the same distribution network, just as it has received weapons from other sources.

The movements from Libya complement the airlift that has variously used Saudi, Jordanian and Qatari military cargo planes to funnel military equipment and weapons, including from Croatia, to the outgunned rebels. On Friday, Syrian opposition officials said the rebels had received a new shipment of anti-tank weapons and other arms, although they give varying accounts of the sources of the recently received arms. The CIA has already played at least a supporting role, the officials say.

The Libyan shipments principally appear to be the work of armed groups there, and not of the weak central state, officials said.

Bukatef said Libyan militias had been shipping weapons to Syrian rebels for more than a year.

"They collect the weapons, and when they have enough they send it," he said. "The Libyan government is not involved, but it does not really matter."

One former senior Obama administration familiar with the transfers said the Qatari government had built relationships with Libyan militias in 2011, when, according to the report of a U.N. Panel of Experts, it shipped in weapons to rebel forces there in violation of U.N. Security Council Resolution 1973.

As a result, the Qataris can draw on their influence with Libya’s militias to support their current beneficiaries in Syria. "It’s not that complicated," the former official said. "We’re watching it. The Libyans have an amazing amount of stuff."

Syrian activists and Western officials say that, like the unregistered arms transfers organized by other Arab states, the shipments from Libya have been very large but have not kept up with the enormous rebel ammunition expenditures each day.

And most of the weapons have been relatively light, including rifles, machine guns, rocket-propelled grenades, small arms ammunition and mortar rounds.

But the Libyan influx appears to account for at least a portion of the anti-tank weapons seen in the conflict this spring, including Belgian-made projectiles for M40 recoilless rifles and some of the Russian-made Konkurs-M guided missiles that have been destroying Syrian tanks in recent months.

Syrian rebels, working with Qatari backers and the Turkish government, have developed a system for acquiring and distributing Libya’s excess stock, Syrian activists and rebels said.

Orders are placed and shipments arranged through the staff of the Supreme Military Council of the Free Syrian Army, a Western-backed opposition committee that was formed in Turkey late last year.

Safi Asafi, a coordinator commander active on Syria’s northern borders, one of the unofficial gates for weapons shipment to the opposition, said rebel groups seeking Libyan arms approached the council to arrange the deals.

"Any fighting group in Syria that wants weapons from Libya will go to the staff asking for the approval from the Turkish authorities involved in the transfer, then gets it, the weapons arrive in Syria, and everyone gets his due share," he said.

By one common formula, Asafi said, the staff will take 20 percent of the weapons designated for individual groups and distribute them to others. The ratio can fluctuate, he said, depending on the group’s stature and influence, and less powerful groups sometimes yield a larger cut.

The Supreme Military Council generally does not distribute weapons to blacklisted or extremist groups, Syrian activists said, but these groups have little trouble acquiring the weapons once the arms enter Syria, often buying them directly from groups that receive the council’s support.

Signs of munitions from the former Gadhafi stockpile are readily visible.

Late last month The found crates, storage sleeves and spent cartridge cases for anti-tank rounds from Libya in the possession of Ahfad al-Rasul, a prominent group fighting the government and aligned with the Supreme Military Council.

The crates were immediately identifiable because they were painted with the distinctive symbol — 412 inside a triangle — that has been used by many manufacturers, including in China, the Soviet Union, Russia, North Korea and Belgium, to mark ordnance shipments designated for Gadhafi.

Stenciling on the crates’ sides declared their original destination in 1980: the Socialist People’s Libyan Arab Jamahiriya.

© 2013 The New York Times Company