Saudi officials have issued increasingly stern warnings against volunteers from the conservative Sunni Muslim kingdom heading off to fight alongside the mainly Sunni rebels trying to oust the Damascus regime.
But diplomats say hundreds of Saudis, perhaps even several thousand, have gone regardless, and judging by death notices and other postings on social networks, their numbers show no sign of abating.
Earlier this month, an Islamist website announced the death of Rashid al-Shelwi, an engineer from the Saudi city of Taif, while fighting alongside the mainstream rebel Free Syrian Army.
On Thursday, the Syrian Observatory for Human Rights reported that a rebel fighter who appeared in a recent video posting executing captured government forces was a Saudi using the nom de guerre Qaswara al-Jazrawi.
Like a significant number of Saudi volunteers, Jazrawi fights in the ranks of the Al-Nusra Front, a US-blacklisted rebel group which has pledged its loyalty to Al-Qaeda, the Britain-based watchdog said.
The involvement of Saudis in jihadist groups has stoked concerns in Riyadh of a resurgence of the deadly Al-Qaeda attacks that rocked the kingdom between 2003 and 2006, and sparked a rare public intervention by King Abdullah.
Without specially referring to the conflict in Syria, the king warned against "those who deceive our children, some of whom have been killed and others imprisoned."
Saudi Arabia's highest religious official, grand mufti Sheikh Abdulaziz Al-Shaikh, chimed in last month with a warning that there was no religious justification for a jihad, or holy war, in Syria.
"The situation in Syria is chaotic due to the proliferation of armed groups that do not fight under a unified banner," the cleric said.
"This is not considered jihad... which must be approved by rulers."
Last June, Saudi Arabia's Council of Senior Ulema, which is headed by Shaikh, already issued a fatwa, or religious edict, prohibiting jihad in Syria without permission from the authorities.
But similar measures failed to stop young Saudis from going to Iraq to fight US-led troops after the overthrow of Saddam Hussein's regime in 2003.
Iraqi officials have said that hundreds of Saudis fought alongside the Sunni insurgents, some of them carrying out suicide attacks against US troops.
"Today, there is a similar issue in Syria -- authorities and religious rulers discourage candidates from jihad," said Stephane Lacroix, a specialist in Saudi Islamism.
Lacroix recalled the price Riyadh had paid for the involvement of thousands of its nationals fighting Soviet troops alongside the mujahedeen in the 1980s, most infamously now slain Al-Qaeda leader Osama bin Laden.
"From the mid-80s, the Saudi authorities gave official support to young Saudis who wanted to go to fight the Soviets," he said.
"A number of these 'Arab Afghans' were later involved in acts of violence in Saudi Arabia."
Saudi officials have sought to play down the number of volunteers in Syria.
Interior ministry spokesman General Mansur al-Turki said last month that he did not believe there were many, and that any that there were would face arrest and interrogation on their return.
General Saeed al-Bishi, head of Prince Mohammed bin Nayef Centre for Counselling and Care, set up to rehabilitate jailed extremists, said his organisation was helping to dissuade young Saudis from fighting in Syria.
"Sometimes parents call to tell us their sons want to go to Syria and we advise them against it," he said.
Authorities are also trying to control the flow of donations from wealthy Saudis to Syrian rebel groups.
Last month, the interior ministry warned against donations to "groups not authorised officially", insisting that all aid must be chanelled through the Saudi Red Crescent and other official bodies.
But Lacroix believes that "in reality, authorities are not capable of monitoring funds that go to jihadist groups fighting in Syria."