A mysterious Libyan ship -- reportedly carrying weapons and bound for Syrian rebels -- may have some link to the Sept. 11 terror attack on the U.S. Consulate in Benghazi, Fox News has learned.

Through shipping records, Fox News has confirmed that the Libyan-flagged vessel Al Entisar, which means "The Victory," was received in the Turkish port of Iskenderun -- 35 miles from the Syrian border -- on Sept. 6, just five days before Ambassador Chris Stevens, information management officer Sean Smith and former Navy Seals Tyrone Woods and Glen Doherty were killed during an extended assault by more than 100 Islamist militants.

On the night of Sept. 11, in what would become his last known public meeting, Stevens met with the Turkish Consul General Ali Sait Akin, and escorted him out of the consulate front gate one hour before the assault began at approximately 9:35 p.m. local time.

Although what was discussed at the meeting is not public, a source told Fox News that Stevens was in Benghazi to negotiate a weapons transfer, an effort to get SA-7 missiles out of the hands of Libya-based extremists. And although the negotiation said to have taken place may have had nothing to do with the attack on the consulate later that night or the Libyan mystery ship, it could explain why Stevens was travelling in such a volatile region on the 11th anniversary of the 9/11 attacks.

When asked to comment, a State Department spokeswoman dismissed the idea, saying Stevens was there for diplomatic meetings, and to attend the opening of a cultural center.

A congressional source also cautioned against drawing premature conclusions about the consulate attack and the movement of weapons from Libya to Syria via Turkey -- noting they may in fact be two separate and distinct events. But the source acknowledged the timing and the meeting between the Turkish diplomat and Stevens was "unusual."

According to an initial Sept. 14 report by the Times of London, Al Entisar was carrying 400 tons of cargo. Some of it was humanitarian, but also reportedly weapons, described by the report as the largest consignment of weapons headed for Syria's rebels on the frontlines.

"This is the Libyan ship ... which is basically carrying weapons that are found in Libya," said Walid Phares, a Fox News Middle East and terrorism analyst. "So the ship came all the way up to Iskenderun in Turkey. Now from the information that is available, there was aid material, but there were also weapons, a lot of weapons."

The cargo reportedly included surface-to-air anti-aircraft missiles, RPG's and Russian-designed shoulder-launched missiles known as MANPADS.

The ship's Libyan captain told the Times of London that "I can only talk about the medicine and humanitarian aid" for the Syrian rebels. It was reported there was a fight about the weapons and who got what "between the free Syrian Army and the Muslim Brotherhood."

"The point is that both of these weapons systems are extremely accurate and very simple to use," Fox News military analyst Col. David Hunt explained. He said the passage of weapons from Libya to Syria would escalate the conflict. "With a short amount of instruction, you've got somebody capable of taking down any, any aircraft. Anywhere in the world."

The Foundation for Human Rights, and Freedoms and Humanitarian Relief (IHH) -- the group accused of moving the weapons -- disputed the claims and in published Turkish reports said it "will take legal action against this article which was written without concrete evidence. It is defamatory, includes false and unfair accusations and violates publishing ethics."

Information uncovered in a Fox News investigation raises questions about whether weapons used to arm the Libyan rebels are now surfacing in Syria.

In March 2011, the Reuters news service first reported that President Obama had authorized a "secret order ... (allowing) covert U.S. government support for rebel forces" to push the Libyan dictator Muammar Qaddafi from office.

At a hearing on March 31, before the House Foreign Affairs Committee, several lawmakers raised concerns about the finding reported by the Reuters news service and whether the Obama administration knew who constituted the rebel forces and whether Islamists were among their ranks.

"What assurances do we have that they will not pose a threat to the United States if they succeed in toppling Qaddafi?" Republican Chairwoman Ileana Ros-Lehtinen, R-Fla., asked. "There are reports that some opposition figures have links to Al Qaeda and extremist groups that have fought against our forces in Iraq."

While the source of the weapons used to attack the consulate is part of an ongoing investigation, former CIA Director Porter Goss told Fox News there was no question some of the weapons that flooded Libya during the uprising are making their way to Syria -- adding that the U.S. intelligence community must be aware, given their presence in Benghazi.

"Absolutely. I think there's no question that there's a lot of networking going on. And ... of course we know it."

A month after the October 2011 death of Qaddafi, Secretary of State Hillary Clinton announced in Tripoli that the U.S. was committing $40 million to help Libya "secure and recover its weapons stockpiles." Earlier this year, Assistant Secretary of State for Political and Military Affairs Andrew Shapiro expressed concerns that the situation on the ground was far from under control.

Speaking to the Stimson Center in Washington D.C., on Feb. 2, Shapiro said: "This raises the question -- how many are still missing? The frank answer is we don't know and probably never will."