It claimed 3,000 tons of weapons dating back to the former Yugoslavia have been sent in 75 planeloads from Zagreb airport to the rebels, largely via Jordan since November.
The story confirmed the origins of ex-Yugoslav weapons seen in growing numbers in rebel hands in online videos, as described last month by The Daily Telegraph and other newspapers, but suggests far bigger quantities than previously suspected.
The shipments were allegedly paid for by Saudi Arabia at the bidding of the United States, with assistance on supplying the weapons organised through Turkey and Jordan, Syria’s neighbours. But the report added that as well as from Croatia, weapons came “from several other European countries including Britain”, without specifying if they were British-supplied or British-procured arms.
British military advisers however are known to be operating in countries bordering Syria alongside French and Americans, offering training to rebel leaders and former Syrian army officers. The Americans are also believed to be providing training on securing chemical weapons sites inside Syria.
President Barack Obama has been lukewarm about arming Syrian rebels though many of his aides have been privately been keener.
The story in the Jutarnji List newspaper gave the fullest details yet of the arms shipments which have enabled rebel forces to begin advancing across the north of Syria in recent weeks, after months of stalemate.
The weapons, including rocket launchers, recoil-less guns and the M79 anti-tank weapon, have been seen in rebel hands in numerous videos, and were first spotted by an arms expert Eliot Higgins, who blogs under the name Brown Moses. He traced them moving from Dera’a in the south, near the Jordanian border, to Aleppo and Idlib provinces in the north.
Western officials told the New York Times that the weapons had been bought from Croatia by Saudi Arabia, and that they had been funnelled to rebel groups seen by the west as more secular and nationalist.
The British involvement fits with the government’s policy of doing all it can to help the rebels within the EU arms embargo, which was modified but not dropped at the start of this month. Croatia, a close western ally, does not join the EU until July 1 and has yet to implement the relevant EU legislation, though it has denied the newspaper’s claims.
The claims were denied by the Foreign Office. “While the Foreign Secretary has ruled out no options for the future, the UK has not supplied weapons to the Syrian opposition,” a spokesman said. “This would be a clear breach of the current EU arms embargo.”
According to the Croat newspaper, the first cargo planes involved with the shipment were from Turkey, but most have been from Jordanian International Air Cargo, whose Russian-made Ilyushin jets have been seen regularly at Zaghreb airport in recent months.
The airlift of dated but effective Yugoslav-made weapons meets key concerns of the West, and especially Turkey and the United States, who want the rebels to be better armed to drive out the Assad regime but fear ultra-modern weaponry getting into the hands of jihadists and the PKK Kurdish terror group.
Nevertheless, Mr Higgins has recently posted videos showing some of the Croat weapons in the hands of the jihadist group Ahrar al-Sham.
Although regarded as hostile to the West, it fights closely with other Free Syrian Army units regarded as acceptable recipients of weapons.